v1.5.1

Lookahead tokens are only need if either:
(1) There is more than one rule that could be reduced in a given parser
state, or
(2) There are shift actions for a state and at least one rule that could
be reduced in the same state (to warn about shift/reduce conflicts).

CHANGELOG.md

@@ -1,3 +1,22 @@
+## v1.5.1
+
+### Improvements
+
+- Improve performance (#28)
+
+## v1.5.0
+
+### New Features
+
+- Track start and end text positions for tokens and rules in AST node structures (#27)
+- Add warnings for shift/reduce conflicts to log file (#25)
+- Add -w command line switch to treat warnings as errors and output to stderr (#26)
+- Add rule field aliases (#24)
+
+### Improvements
+
+- Show line numbers of rules on conflict (#23)
+
 ## v1.4.0
 
 ### New Features

README.md

@@ -31,9 +31,14 @@ Propane is typically invoked from the command-line as `./propane`.
 
     Usage: ./propane [options] <input-file> <output-file>
     Options:
-      --log LOG   Write log file
-      --version   Show program version and exit
-      -h, --help  Show this usage and exit
+      -h, --help  Show this usage and exit.
+      --log LOG   Write log file. This will show all parser states and their
+                  associated shifts and reduces. It can be helpful when
+                  debugging a grammar.
+      --version   Show program version and exit.
+      -w          Treat warnings as errors. This option will treat shift/reduce
+                  conflicts as fatal errors and will print them to stderr in
+                  addition to the log file.
 
 The user must specify the path to a Propane input grammar file and a path to an
 output file.

assets/parser.c.erb

@@ -226,7 +226,10 @@ typedef struct
     /** Number of bytes of input text used to match. */
     size_t length;
 
-    /** Input text position delta. */
+    /** Input text position delta to end of token. */
+    <%= @grammar.prefix %>position_t end_delta_position;
+
+    /** Input text position delta to next code point after token end. */
     <%= @grammar.prefix %>position_t delta_position;
 
     /** Accepting lexer state from the match. */
@@ -358,6 +361,7 @@ static size_t find_longest_match(<%= @grammar.prefix %>context_t * context,
             if (transition_state != INVALID_LEXER_STATE_ID)
             {
                 attempt_match.length += code_point_length;
+                attempt_match.end_delta_position = attempt_match.delta_position;
                 if (code_point == '\n')
                 {
                     attempt_match.delta_position.row++;
@@ -444,7 +448,6 @@ static size_t attempt_lex_token(<%= @grammar.prefix %>context_t * context, <%= @
     <%= @grammar.prefix %>token_info_t token_info = {0};
     token_info.position = context->text_position;
     token_info.token = INVALID_TOKEN_ID;
-    *out_token_info = token_info; // TODO: remove
     lexer_match_info_t match_info;
     size_t unexpected_input_length;
     size_t result = find_longest_match(context, &match_info, &unexpected_input_length);
@@ -491,11 +494,22 @@ static size_t attempt_lex_token(<%= @grammar.prefix %>context_t * context, <%= @
         }
         token_info.token = token_to_accept;
         token_info.length = match_info.length;
+        if (match_info.end_delta_position.row != 0u)
+        {
+            token_info.end_position.row = token_info.position.row + match_info.end_delta_position.row;
+            token_info.end_position.col = match_info.end_delta_position.col;
+        }
+        else
+        {
+            token_info.end_position.row = token_info.position.row;
+            token_info.end_position.col = token_info.position.col + match_info.end_delta_position.col;
+        }
         *out_token_info = token_info;
         return P_SUCCESS;
 
     case P_EOF:
         token_info.token = TOKEN___EOF;
+        token_info.end_position = token_info.position;
         *out_token_info = token_info;
         return P_SUCCESS;
 
@@ -552,6 +566,9 @@ size_t <%= @grammar.prefix %>lex(<%= @grammar.prefix %>context_t * context, <%=
  * Parser
  *************************************************************************/
 
+/** Invalid position value. */
+#define INVALID_POSITION (<%= @grammar.prefix %>position_t){0xFFFFFFFFu, 0xFFFFFFFFu}
+
 /** Reduce ID type. */
 typedef <%= get_type_for(@parser.reduce_table.size) %> reduce_id_t;
 
@@ -667,10 +684,18 @@ typedef struct
 <% end %>
 } state_value_t;
 
+/** Common AST node structure. */
+typedef struct
+{
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
+    void * fields[];
+} ASTNode;
+
 /** Parser shift table. */
 static const shift_t parser_shift_table[] = {
 <%   @parser.shift_table.each do |shift| %>
-    {<%= shift[:symbol_id] %>u, <%= shift[:state_id] %>u},
+    {<%= shift[:symbol].id %>u, <%= shift[:state_id] %>u},
 <%   end %>
 };
 
@@ -950,6 +975,8 @@ size_t <%= @grammar.prefix %>parse(<%= @grammar.prefix %>context_t * context)
                 /* We shifted a token, mark it consumed. */
 <% if @grammar.ast %>
                 <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %> * token_ast_node = malloc(sizeof(<%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>));
+                token_ast_node->position = token_info.position;
+                token_ast_node->end_position = token_info.end_position;
                 token_ast_node->token = token;
                 token_ast_node->pvalue = token_info.pvalue;
                 state_values_stack_index(&statevalues, -1)->ast_node = token_ast_node;
@@ -984,22 +1011,43 @@ size_t <%= @grammar.prefix %>parse(<%= @grammar.prefix %>context_t * context)
             }
             else if (parser_reduce_table[reduce_index].n_states > 0)
             {
-                void ** node_fields = calloc(parser_reduce_table[reduce_index].rule_set_node_field_array_size, sizeof(void *));
+                size_t n_fields = parser_reduce_table[reduce_index].rule_set_node_field_array_size;
+                ASTNode * node = (ASTNode *)malloc(sizeof(ASTNode) + n_fields * sizeof(void *));
+                node->position = INVALID_POSITION;
+                node->end_position = INVALID_POSITION;
+                for (size_t i = 0; i < n_fields; i++)
+                {
+                    node->fields[i] = NULL;
+                }
                 if (parser_reduce_table[reduce_index].rule_set_node_field_index_map == NULL)
                 {
                     for (size_t i = 0; i < parser_reduce_table[reduce_index].n_states; i++)
                     {
-                        node_fields[i] = state_values_stack_index(&statevalues, -(int)parser_reduce_table[reduce_index].n_states + (int)i)->ast_node;
+                        node->fields[i] = state_values_stack_index(&statevalues, -(int)parser_reduce_table[reduce_index].n_states + (int)i)->ast_node;
                     }
                 }
                 else
                 {
                     for (size_t i = 0; i < parser_reduce_table[reduce_index].n_states; i++)
                     {
-                        node_fields[parser_reduce_table[reduce_index].rule_set_node_field_index_map[i]] = state_values_stack_index(&statevalues, -(int)parser_reduce_table[reduce_index].n_states + (int)i)->ast_node;
+                        node->fields[parser_reduce_table[reduce_index].rule_set_node_field_index_map[i]] = state_values_stack_index(&statevalues, -(int)parser_reduce_table[reduce_index].n_states + (int)i)->ast_node;
                     }
                 }
-                reduced_parser_node = node_fields;
+                bool position_found = false;
+                for (size_t i = 0; i < n_fields; i++)
+                {
+                    ASTNode * child = (ASTNode *)node->fields[i];
+                    if ((child != NULL) && <%= @grammar.prefix %>position_valid(child->position))
+                    {
+                        if (!position_found)
+                        {
+                            node->position = child->position;
+                            position_found = true;
+                        }
+                        node->end_position = child->end_position;
+                    }
+                }
+                reduced_parser_node = node;
             }
             else
             {

assets/parser.d.erb

@@ -8,6 +8,8 @@
 module <%= @grammar.modulename %>;
 <% end %>
 
+import core.stdc.stdlib : malloc;
+
 /**************************************************************************
  * User code blocks
  *************************************************************************/
@@ -49,6 +51,29 @@ public enum : <%= @grammar.prefix %>token_t
 /** Code point type. */
 public alias <%= @grammar.prefix %>code_point_t = uint;
 
+/**
+ * A structure to keep track of input position.
+ *
+ * This is useful for reporting errors, etc...
+ */
+public struct <%= @grammar.prefix %>position_t
+{
+    /** Input text row (0-based). */
+    uint row;
+
+    /** Input text column (0-based). */
+    uint col;
+
+    /** Invalid position value. */
+    enum INVALID = <%= @grammar.prefix %>position_t(0xFFFF_FFFF, 0xFFFF_FFFF);
+
+    /** Return whether the position is valid. */
+    public @property bool valid()
+    {
+        return row != 0xFFFF_FFFFu;
+    }
+}
+
 <% if @grammar.ast %>
 /** Parser values type. */
 public alias <%= @grammar.prefix %>value_t = <%= @grammar.ptype %>;
@@ -63,9 +88,20 @@ public union <%= @grammar.prefix %>value_t
 <% end %>
 
 <% if @grammar.ast %>
+/** Common AST node structure. */
+private struct ASTNode
+{
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
+    void *[0] fields;
+}
+
 /** AST node types. @{ */
 public struct <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>
 {
+    /* ASTNode fields must be present in the same order here. */
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
     <%= @grammar.prefix %>token_t token;
     <%= @grammar.prefix %>value_t pvalue;
 }
@@ -75,6 +111,8 @@ public struct <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>
 <%     next if rule_set.optional? %>
 public struct <%= @grammar.ast_prefix %><%= name %><%= @grammar.ast_suffix %>
 {
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
 <%     rule_set.ast_fields.each do |fields| %>
     union
     {
@@ -89,26 +127,15 @@ public struct <%= @grammar.ast_prefix %><%= name %><%= @grammar.ast_suffix %>
 /** @} */
 <% end %>
 
-/**
- * A structure to keep track of parser position.
- *
- * This is useful for reporting errors, etc...
- */
-public struct <%= @grammar.prefix %>position_t
-{
-    /** Input text row (0-based). */
-    uint row;
-
-    /** Input text column (0-based). */
-    uint col;
-}
-
 /** Lexed token information. */
 public struct <%= @grammar.prefix %>token_info_t
 {
-    /** Text position where the token was found. */
+    /** Text position of first code point in token. */
     <%= @grammar.prefix %>position_t position;
 
+    /** Text position of last code point in token. */
+    <%= @grammar.prefix %>position_t end_position;
+
     /** Number of input bytes used by the token. */
     size_t length;
 
@@ -372,7 +399,10 @@ private struct lexer_match_info_t
     /** Number of bytes of input text used to match. */
     size_t length;
 
-    /** Input text position delta. */
+    /** Input text position delta to end of token. */
+    <%= @grammar.prefix %>position_t end_delta_position;
+
+    /** Input text position delta to next code point after token end. */
     <%= @grammar.prefix %>position_t delta_position;
 
     /** Accepting lexer state from the match. */
@@ -500,6 +530,7 @@ private size_t find_longest_match(<%= @grammar.prefix %>context_t * context,
             if (transition_state != INVALID_LEXER_STATE_ID)
             {
                 attempt_match.length += code_point_length;
+                attempt_match.end_delta_position = attempt_match.delta_position;
                 if (code_point == '\n')
                 {
                     attempt_match.delta_position.row++;
@@ -586,7 +617,6 @@ private size_t attempt_lex_token(<%= @grammar.prefix %>context_t * context, <%=
     <%= @grammar.prefix %>token_info_t token_info;
     token_info.position = context.text_position;
     token_info.token = INVALID_TOKEN_ID;
-    *out_token_info = token_info; // TODO: remove
     lexer_match_info_t match_info;
     size_t unexpected_input_length;
     size_t result = find_longest_match(context, &match_info, &unexpected_input_length);
@@ -633,11 +663,22 @@ private size_t attempt_lex_token(<%= @grammar.prefix %>context_t * context, <%=
         }
         token_info.token = token_to_accept;
         token_info.length = match_info.length;
+        if (match_info.end_delta_position.row != 0u)
+        {
+            token_info.end_position.row = token_info.position.row + match_info.end_delta_position.row;
+            token_info.end_position.col = match_info.end_delta_position.col;
+        }
+        else
+        {
+            token_info.end_position.row = token_info.position.row;
+            token_info.end_position.col = token_info.position.col + match_info.end_delta_position.col;
+        }
         *out_token_info = token_info;
         return P_SUCCESS;
 
     case P_EOF:
         token_info.token = TOKEN___EOF;
+        token_info.end_position = token_info.position;
         *out_token_info = token_info;
         return P_SUCCESS;
 
@@ -817,7 +858,7 @@ private struct state_value_t
 /** Parser shift table. */
 private immutable shift_t[] parser_shift_table = [
 <%   @parser.shift_table.each do |shift| %>
-    shift_t(<%= shift[:symbol_id] %>u, <%= shift[:state_id] %>u),
+    shift_t(<%= shift[:symbol].id %>u, <%= shift[:state_id] %>u),
 <%   end %>
 ];
 
@@ -997,7 +1038,7 @@ public size_t <%= @grammar.prefix %>parse(<%= @grammar.prefix %>context_t * cont
             {
                 /* We shifted a token, mark it consumed. */
 <% if @grammar.ast %>
-                <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %> * token_ast_node = new <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>(token, token_info.pvalue);
+                <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %> * token_ast_node = new <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>(token_info.position, token_info.end_position, token, token_info.pvalue);
                 statevalues[$-1].ast_node = token_ast_node;
 <% else %>
                 statevalues[$-1].pvalue = token_info.pvalue;
@@ -1030,26 +1071,43 @@ public size_t <%= @grammar.prefix %>parse(<%= @grammar.prefix %>context_t * cont
             }
             else if (parser_reduce_table[reduce_index].n_states > 0)
             {
-                void *[] node_fields = new void *[parser_reduce_table[reduce_index].rule_set_node_field_array_size];
-                foreach (i; 0..parser_reduce_table[reduce_index].rule_set_node_field_array_size)
+                size_t n_fields = parser_reduce_table[reduce_index].rule_set_node_field_array_size;
+                ASTNode * node = cast(ASTNode *)malloc(ASTNode.sizeof + n_fields * (void *).sizeof);
+                node.position = <%= @grammar.prefix %>position_t.INVALID;
+                node.end_position = <%= @grammar.prefix %>position_t.INVALID;
+                foreach (i; 0..n_fields)
                 {
-                    node_fields[i] = null;
+                    node.fields[i] = null;
                 }
                 if (parser_reduce_table[reduce_index].rule_set_node_field_index_map is null)
                 {
                     foreach (i; 0..parser_reduce_table[reduce_index].n_states)
                     {
-                        node_fields[i] = statevalues[$ - parser_reduce_table[reduce_index].n_states + i].ast_node;
+                        node.fields[i] = statevalues[$ - parser_reduce_table[reduce_index].n_states + i].ast_node;
                     }
                 }
                 else
                 {
                     foreach (i; 0..parser_reduce_table[reduce_index].n_states)
                     {
-                        node_fields[parser_reduce_table[reduce_index].rule_set_node_field_index_map[i]] = statevalues[$ - parser_reduce_table[reduce_index].n_states + i].ast_node;
+                        node.fields[parser_reduce_table[reduce_index].rule_set_node_field_index_map[i]] = statevalues[$ - parser_reduce_table[reduce_index].n_states + i].ast_node;
                     }
                 }
-                reduced_parser_node = node_fields.ptr;
+                bool position_found = false;
+                foreach (i; 0..n_fields)
+                {
+                    ASTNode * child = cast(ASTNode *)node.fields[i];
+                    if (child && child.position.valid)
+                    {
+                        if (!position_found)
+                        {
+                            node.position = child.position;
+                            position_found = true;
+                        }
+                        node.end_position = child.end_position;
+                    }
+                }
+                reduced_parser_node = node;
             }
             else
             {

assets/parser.h.erb

@@ -38,6 +38,23 @@ typedef <%= get_type_for(@grammar.terminate_token_id) %> <%= @grammar.prefix %>t
 /** Code point type. */
 typedef uint32_t <%= @grammar.prefix %>code_point_t;
 
+/**
+ * A structure to keep track of input position.
+ *
+ * This is useful for reporting errors, etc...
+ */
+typedef struct
+{
+    /** Input text row (0-based). */
+    uint32_t row;
+
+    /** Input text column (0-based). */
+    uint32_t col;
+} <%= @grammar.prefix %>position_t;
+
+/** Return whether the position is valid. */
+#define <%= @grammar.prefix %>position_valid(p) ((p).row != 0xFFFFFFFFu)
+
 /** User header code blocks. */
 <%= @grammar.code_blocks.fetch("header", "") %>
 
@@ -58,6 +75,9 @@ typedef union
 /** AST node types. @{ */
 typedef struct <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>
 {
+    /* ASTNode fields must be present in the same order here. */
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
     <%= @grammar.prefix %>token_t token;
     <%= @grammar.prefix %>value_t pvalue;
 } <%= @grammar.ast_prefix %>Token<%= @grammar.ast_suffix %>;
@@ -73,6 +93,8 @@ struct <%= name %>;
 <%     next if rule_set.optional? %>
 typedef struct <%= @grammar.ast_prefix %><%= name %><%= @grammar.ast_suffix %>
 {
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
 <%     rule_set.ast_fields.each do |fields| %>
     union
     {
@@ -87,26 +109,15 @@ typedef struct <%= @grammar.ast_prefix %><%= name %><%= @grammar.ast_suffix %>
 /** @} */
 <% end %>
 
-/**
- * A structure to keep track of parser position.
- *
- * This is useful for reporting errors, etc...
- */
-typedef struct
-{
-    /** Input text row (0-based). */
-    uint32_t row;
-
-    /** Input text column (0-based). */
-    uint32_t col;
-} <%= @grammar.prefix %>position_t;
-
 /** Lexed token information. */
 typedef struct
 {
-    /** Text position where the token was found. */
+    /** Text position of first code point in token. */
     <%= @grammar.prefix %>position_t position;
 
+    /** Text position of last code point in token. */
+    <%= @grammar.prefix %>position_t end_position;
+
     /** Number of input bytes used by the token. */
     size_t length;
 

doc/user_guide.md

@@ -15,6 +15,7 @@ Propane is a LALR Parser Generator (LPG) which:
   * generates a table-driven shift/reduce parser to parse input in linear time
   * targets C or D language outputs
   * optionally supports automatic full AST generation
+  * tracks input text start and end positions for all matched tokens/rules
   * is MIT-licensed
   * is distributable as a standalone Ruby script
 
@@ -35,9 +36,14 @@ Propane is typically invoked from the command-line as `./propane`.
 
     Usage: ./propane [options] <input-file> <output-file>
     Options:
-      --log LOG   Write log file
-      --version   Show program version and exit
-      -h, --help  Show this usage and exit
+      -h, --help  Show this usage and exit.
+      --log LOG   Write log file. This will show all parser states and their
+                  associated shifts and reduces. It can be helpful when
+                  debugging a grammar.
+      --version   Show program version and exit.
+      -w          Treat warnings as errors. This option will treat shift/reduce
+                  conflicts as fatal errors and will print them to stderr in
+                  addition to the log file.
 
 The user must specify the path to a Propane input grammar file and a path to an
 output file.
@@ -228,15 +234,15 @@ drop /\\s+/;
 
 Start -> Items;
 
-Items -> Item ItemsMore;
+Items -> Item:item ItemsMore;
 Items -> ;
 
-ItemsMore -> comma Item ItemsMore;
+ItemsMore -> comma Item:item ItemsMore;
 ItemsMore -> ;
 
 Item -> a;
 Item -> b;
-Item -> lparen Item rparen;
+Item -> lparen Item:item rparen;
 Item -> Dual;
 
 Dual -> One Two;
@@ -257,24 +263,24 @@ Start * start = p_result(&context);
 assert(start.pItems1 !is null);
 assert(start.pItems !is null);
 Items * items = start.pItems;
-assert(items.pItem !is null);
-assert(items.pItem.pToken1 !is null);
-assert_eq(TOKEN_a, items.pItem.pToken1.token);
-assert_eq(11, items.pItem.pToken1.pvalue);
+assert(items.item !is null);
+assert(items.item.pToken1 !is null);
+assert_eq(TOKEN_a, items.item.pToken1.token);
+assert_eq(11, items.item.pToken1.pvalue);
 assert(items.pItemsMore !is null);
 ItemsMore * itemsmore = items.pItemsMore;
-assert(itemsmore.pItem !is null);
-assert(itemsmore.pItem.pItem !is null);
-assert(itemsmore.pItem.pItem.pItem !is null);
-assert(itemsmore.pItem.pItem.pItem.pToken1 !is null);
-assert_eq(TOKEN_b, itemsmore.pItem.pItem.pItem.pToken1.token);
-assert_eq(22, itemsmore.pItem.pItem.pItem.pToken1.pvalue);
+assert(itemsmore.item !is null);
+assert(itemsmore.item.item !is null);
+assert(itemsmore.item.item.item !is null);
+assert(itemsmore.item.item.item.pToken1 !is null);
+assert_eq(TOKEN_b, itemsmore.item.item.item.pToken1.token);
+assert_eq(22, itemsmore.item.item.item.pToken1.pvalue);
 assert(itemsmore.pItemsMore !is null);
 itemsmore = itemsmore.pItemsMore;
-assert(itemsmore.pItem !is null);
-assert(itemsmore.pItem.pToken1 !is null);
-assert_eq(TOKEN_b, itemsmore.pItem.pToken1.token);
-assert_eq(22, itemsmore.pItem.pToken1.pvalue);
+assert(itemsmore.item !is null);
+assert(itemsmore.item.pToken1 !is null);
+assert_eq(TOKEN_b, itemsmore.item.pToken1.token);
+assert_eq(22, itemsmore.item.pToken1.pvalue);
 assert(itemsmore.pItemsMore is null);
 ```
 
@@ -502,7 +508,7 @@ tokenid str;
   mystringvalue = "";
   $mode(string);
 >>
-string: /[^"]+/ << mystringvalue += match; >>
+string: /[^"]+/ << mystringvalue ~= match; >>
 string: /"/ <<
   $mode(default);
   return $token(str);
@@ -601,6 +607,10 @@ This can be changed with the `start` statement.
 The grammar file must define a rule with the name of the start rule name which
 will be used as the top-level starting rule that the parser attempts to reduce.
 
+Rule statements are composed of the name of the rule, a `->` token, the fields
+defining the rule pattern that must be matched, and a terminating semicolon or
+user code block.
+
 Example:
 
 ```
@@ -629,9 +639,13 @@ E4 -> lparen E1 rparen << $$ = $2; >>
 
 This example uses the default start rule name of `Start`.
 
-A parser rule has zero or more terms on the right side of its definition.
-Each of these terms is either a token name or a rule name.
-A term can be immediately followed by a `?` character to signify that it is
+A parser rule has zero or more fields on the right side of its definition.
+Each of these fields is either a token name or a rule name.
+A field can optionally be followed by a `:` and then a field alias name.
+If present, the field alias name is used to refer to the field value in user
+code blocks, or if AST mode is active, the field alias name is used as the
+field name in the generated AST node structure.
+A field can be immediately followed by a `?` character to signify that it is
 optional.
 Another example:
 
@@ -641,14 +655,16 @@ token private;
 token int;
 token ident /[a-zA-Z_][a-zA-Z_0-9]*/;
 token semicolon /;/;
-IntegerDeclaration -> Visibility? int ident semicolon;
+IntegerDeclaration -> Visibility? int ident:name semicolon;
 Visibility -> public;
 Visibility -> private;
 ```
 
-In a parser rule code block, parser values for the right side terms are
-accessible as `$1` for the first term's parser value, `$2` for the second
-term's parser value, etc...
+In a parser rule code block, parser values for the right side fields are
+accessible as `$1` for the first field's parser value, `$2` for the second
+field's parser value, etc...
+For the `IntegerDeclaration` rule, the third field value can also be referred
+to as `${name}`.
 The `$$` symbol accesses the output parser value for this rule.
 The above examples demonstrate how the parser values for the rule components
 can be used to produce the parser value for the accepted rule.
@@ -762,6 +778,13 @@ A pointer to this instance is passed to the generated functions.
 The `p_position_t` structure contains two fields `row` and `col`.
 These fields contain the 0-based row and column describing a parser position.
 
+For D targets, the `p_position_t` structure can be checked for validity by
+querying the `valid` property.
+
+For C targets, the `p_position_t` structure can be checked for validity by
+calling `p_position_valid(pos)` where `pos` is a `p_position_t` structure
+instance.
+
 ### AST Node Types
 
 If AST generation mode is enabled, a structure type for each rule will be
@@ -772,13 +795,26 @@ AST node which refers to a raw parser token rather than a composite rule.
 
 #### AST Node Fields
 
-A `Token` node has two fields:
+All AST nodes have a `position` field specifying the text position of the
+beginning of the matched token or rule, and an `end_position` field specifying
+the text position of the end of the matched token or rule.
+Each of these fields are instances of the `p_position_t` structure.
+
+A `Token` node will always have a valid `position` and `end_position`.
+A rule node may not have valid positions if the rule allows for an empty match.
+In this case the `position` structure should be checked for validity before
+using it.
+For C targets this can be accomplished with
+`if (p_position_valid(node->position))` and for D targets this can be
+accomplished with `if (node.position.valid)`.
+
+A `Token` node has the following additional fields:
 
   * `token` which specifies which token was parsed (one of `TOKEN_*`)
   * `pvalue` which specifies the parser value for the token. If a lexer user
   code block assigned to `$$`, the assigned value will be stored here.
 
-The other generated AST node structures have fields generated based on the
+AST node structures for rules contain generated fields based on the
 right hand side components specified for all rules of a given name.
 
 In this example:
@@ -802,7 +838,7 @@ The `Items` structure will have fields:
 
 If a rule can be empty (for example in the second `Items` rule above), then
 an instance of a pointer to that rule's generated AST node will be null if the
-parser matches the empty rule definition.
+parser matches the empty rule pattern.
 
 The non-positional AST node field pointer will not be generated if there are
 multiple positions in which an instance of the node it points to could be
@@ -823,6 +859,19 @@ If the first rule is matched, then `pOne1` and `pTwo2` will be non-null while
 `pTwo1` and `pOne2` will be null.
 If the second rule is matched instead, then the opposite would be the case.
 
+If a field alias is present in a rule definition, an additional field will be
+generated in the AST node with the field alias name.
+For example:
+
+```
+Exp -> Exp:left plus ExpB:right;
+```
+
+In the generated `Exp` structure, the fields `pExp`, `pExp1`, and `left` will
+all point to the same child node (an instance of the `Exp` structure), and the
+fields `pExpB`, `pExpB3`, and `right` will all point to the same child node
+(an instance of the `ExpB` structure).
+
 ##> Functions
 
 ### `p_context_init`
@@ -859,6 +908,24 @@ p_context_init(&context, input, input_length);
 size_t result = p_parse(&context);
 ```
 
+### `p_position_valid`
+
+The `p_position_valid()` function is only generated for C targets.
+it is used to determine whether or not a `p_position_t` structure is valid.
+
+Example:
+
+```
+if (p_position_valid(node->position))
+{
+    ....
+}
+```
+
+For D targets, rather than using `p_position_valid()`, the `valid` property
+function of the `p_position_t` structure can be queried
+(e.g. `if (node.position.valid)`).
+
 ### `p_result`
 
 The `p_result()` function can be used to retrieve the final parse value after

extra/vim/ftdetect/propane.vim

@@ -0,0 +1 @@
+au BufNewFile,BufRead *.propane set filetype=propane

extra/vim/syntax/propane.vim

@@ -0,0 +1,33 @@
+" Vim syntax file for Propane
+" Language: propane
+" Maintainer: Josh Holtrop
+" URL: https://github.com/holtrop/propane
+
+if exists("b:current_syntax")
+  finish
+endif
+
+if !exists("b:propane_subtype")
+  let b:propane_subtype = "d"
+endif
+
+exe "syn include @propaneTarget syntax/".b:propane_subtype.".vim"
+
+syn region propaneTarget matchgroup=propaneDelimiter start="<<" end=">>$" contains=@propaneTarget keepend
+
+syn match propaneComment "#.*"
+syn match propaneOperator "->"
+syn match propaneFieldAlias ":[a-zA-Z0-9_]\+" contains=propaneFieldOperator
+syn match propaneFieldOperator ":" contained
+syn match propaneOperator "?"
+syn keyword propaneKeyword ast ast_prefix ast_suffix drop module prefix ptype start token tokenid
+
+syn region propaneRegex start="/" end="/" skip="\\/"
+
+hi def link propaneComment Comment
+hi def link propaneKeyword Keyword
+hi def link propaneRegex String
+hi def link propaneOperator Operator
+hi def link propaneFieldOperator Operator
+hi def link propaneDelimiter Delimiter
+hi def link propaneFieldAlias Identifier

lib/propane.rb

@@ -31,10 +31,10 @@ class Propane
 
   class << self
 
-    def run(input_file, output_file, log_file)
+    def run(input_file, output_file, log_file, options)
       begin
         grammar = Grammar.new(File.read(input_file))
-        generator = Generator.new(grammar, output_file, log_file)
+        generator = Generator.new(grammar, output_file, log_file, options)
         generator.generate
       rescue Error => e
         $stderr.puts e.message

lib/propane/cli.rb

@@ -4,15 +4,21 @@ class Propane
     USAGE = <<EOF
 Usage: #{$0} [options] <input-file> <output-file>
 Options:
-  --log LOG   Write log file
-  --version   Show program version and exit
-  -h, --help  Show this usage and exit
+  -h, --help  Show this usage and exit.
+  --log LOG   Write log file. This will show all parser states and their
+              associated shifts and reduces. It can be helpful when
+              debugging a grammar.
+  --version   Show program version and exit.
+  -w          Treat warnings as errors. This option will treat shift/reduce
+              conflicts as fatal errors and will print them to stderr in
+              addition to the log file.
 EOF
 
     class << self
 
       def run(args)
         params = []
+        options = {}
         log_file = nil
         i = 0
         while i < args.size
@@ -29,6 +35,8 @@ EOF
           when "-h", "--help"
             puts USAGE
             return 0
+          when "-w"
+            options[:warnings_as_errors] = true
           when /^-/
             $stderr.puts "Error: unknown option #{arg}"
             return 1
@@ -45,7 +53,7 @@ EOF
           $stderr.puts "Error: cannot read #{params[0]}"
           return 2
         end
-        Propane.run(*params, log_file)
+        Propane.run(*params, log_file, options)
       end
 
     end

lib/propane/generator.rb

@@ -2,7 +2,7 @@ class Propane
 
   class Generator
 
-    def initialize(grammar, output_file, log_file)
+    def initialize(grammar, output_file, log_file, options)
       @grammar = grammar
       @output_file = output_file
       if log_file
@@ -16,6 +16,7 @@ class Propane
         else
           "d"
         end
+      @options = options
       process_grammar!
     end
 
@@ -129,7 +130,7 @@ class Propane
       # Generate the lexer.
       @lexer = Lexer.new(@grammar)
       # Generate the parser.
-      @parser = Parser.new(@grammar, rule_sets, @log)
+      @parser = Parser.new(@grammar, rule_sets, @log, @options)
     end
 
     # Check that any referenced ptypes have been defined.
@@ -275,6 +276,19 @@ class Propane
             "statevalues[$-1-n_states+#{index}].pvalue.v_#{rule.components[index - 1].ptypename}"
           end
         end
+        code = code.gsub(/\$\{(\w+)\}/) do |match|
+          aliasname = $1
+          if index = rule.aliases[aliasname]
+            case @language
+            when "c"
+              "state_values_stack_index(statevalues, -(int)n_states + #{index})->pvalue.v_#{rule.components[index].ptypename}"
+            when "d"
+              "statevalues[$-n_states+#{index}].pvalue.v_#{rule.components[index].ptypename}"
+            end
+          else
+            raise Error.new("Field alias '#{aliasname}' not found")
+          end
+        end
       else
         code = code.gsub(/\$\$/) do |match|
           if @grammar.ast

lib/propane/grammar.rb

@@ -198,7 +198,7 @@ class Propane
         if @ast && ptypename
           raise Error.new("Multiple ptypes are unsupported in AST mode")
         end
-        md = consume!(/((?:#{IDENTIFIER_REGEX}\??\s*)*)\s*/, "expected rule component list")
+        md = consume!(/((?:#{IDENTIFIER_REGEX}(?::#{IDENTIFIER_REGEX})?\??\s*)*)\s*/, "expected rule component list")
         components = md[1].strip.split(/\s+/)
         if @ast
           consume!(/;/, "expected `;'")

lib/propane/parser.rb

@@ -7,12 +7,14 @@ class Propane
     attr_reader :reduce_table
     attr_reader :rule_sets
 
-    def initialize(grammar, rule_sets, log)
+    def initialize(grammar, rule_sets, log, options)
       @grammar = grammar
       @rule_sets = rule_sets
       @log = log
       @item_sets = []
       @item_sets_set = {}
+      @warnings = Set.new
+      @options = options
       start_item = Item.new(grammar.rules.first, 0)
       eval_item_sets = Set[ItemSet.new([start_item])]
 
@@ -23,10 +25,10 @@ class Propane
           item_set.id = @item_sets.size
           @item_sets << item_set
           @item_sets_set[item_set] = item_set
-          item_set.following_symbols.each do |following_symbol|
-            unless following_symbol.name == "$EOF"
-              following_set = item_set.build_following_item_set(following_symbol)
-              eval_item_sets << following_set
+          item_set.next_symbols.each do |next_symbol|
+            unless next_symbol.name == "$EOF"
+              next_item_set = item_set.build_next_item_set(next_symbol)
+              eval_item_sets << next_item_set
             end
           end
         end
@@ -37,8 +39,11 @@ class Propane
       end
 
       build_reduce_actions!
-      write_log!
       build_tables!
+      write_log!
+      if @warnings.size > 0 && @options[:warnings_as_errors]
+        raise Error.new("Fatal errors (-w):\n" + @warnings.join("\n"))
+      end
     end
 
     private
@@ -48,26 +53,34 @@ class Propane
       @shift_table = []
       @reduce_table = []
       @item_sets.each do |item_set|
-        shift_entries = item_set.following_symbols.map do |following_symbol|
+        shift_entries = item_set.next_symbols.map do |next_symbol|
           state_id =
-            if following_symbol.name == "$EOF"
+            if next_symbol.name == "$EOF"
               0
             else
-              item_set.following_item_set[following_symbol].id
+              item_set.next_item_set[next_symbol].id
             end
           {
-            symbol_id: following_symbol.id,
+            symbol: next_symbol,
             state_id: state_id,
           }
         end
+        unless item_set.reduce_rules.empty?
+          shift_entries.each do |shift_entry|
+            token = shift_entry[:symbol]
+            if get_lookahead_reduce_actions_for_item_set(item_set).include?(token)
+              rule = item_set.reduce_actions[token]
+              @warnings << "Shift/Reduce conflict (state #{item_set.id}) between token #{token.name} and rule #{rule.name} (defined on line #{rule.line_number})"
+            end
+          end
+        end
         reduce_entries =
-          case ra = item_set.reduce_actions
-          when Rule
-            [{token_id: @grammar.invalid_token_id, rule_id: ra.id, rule: ra,
-              rule_set_id: ra.rule_set.id, n_states: ra.components.size,
-              propagate_optional_target: ra.optional? && ra.components.size == 1}]
-          when Hash
-            ra.map do |token, rule|
+          if rule = item_set.reduce_rule
+            [{token_id: @grammar.invalid_token_id, rule_id: rule.id, rule: rule,
+              rule_set_id: rule.rule_set.id, n_states: rule.components.size,
+              propagate_optional_target: rule.optional? && rule.components.size == 1}]
+          elsif reduce_actions = item_set.reduce_actions
+            reduce_actions.map do |token, rule|
               {token_id: token.id, rule_id: rule.id, rule: rule,
                rule_set_id: rule.rule_set.id, n_states: rule.components.size,
                propagate_optional_target: rule.optional? && rule.components.size == 1}
@@ -87,11 +100,11 @@ class Propane
     end
 
     def process_item_set(item_set)
-      item_set.following_symbols.each do |following_symbol|
-        unless following_symbol.name == "$EOF"
-          following_set = @item_sets_set[item_set.build_following_item_set(following_symbol)]
-          item_set.following_item_set[following_symbol] = following_set
-          following_set.in_sets << item_set
+      item_set.next_symbols.each do |next_symbol|
+        unless next_symbol.name == "$EOF"
+          next_item_set = @item_sets_set[item_set.build_next_item_set(next_symbol)]
+          item_set.next_item_set[next_symbol] = next_item_set
+          next_item_set.in_sets << item_set
         end
       end
     end
@@ -101,7 +114,7 @@ class Propane
     # @return [void]
     def build_reduce_actions!
       @item_sets.each do |item_set|
-        item_set.reduce_actions = build_reduce_actions_for_item_set(item_set)
+        build_reduce_actions_for_item_set(item_set)
       end
     end
 
@@ -110,38 +123,55 @@ class Propane
     # @param item_set [ItemSet]
     #   ItemSet (parser state)
     #
-    # @return [nil, Rule, Hash]
-    #   If no reduce actions are possible for the given item set, nil.
-    #   If only one reduce action is possible for the given item set, the Rule
-    #   to reduce.
-    #   Otherwise, a mapping of lookahead Tokens to the Rules to reduce.
+    # @return [void]
     def build_reduce_actions_for_item_set(item_set)
       # To build the reduce actions, we start by looking at any
       # "complete" items, i.e., items where the parse position is at the
       # end of a rule. These are the only rules that are candidates for
       # reduction in the current ItemSet.
-      reduce_rules = Set.new(item_set.items.select(&:complete?).map(&:rule))
+      item_set.reduce_rules = Set.new(item_set.items.select(&:complete?).map(&:rule))
 
-      # If there are no rules to reduce for this ItemSet, we're done here.
-      return nil if reduce_rules.size == 0
+      if item_set.reduce_rules.size == 1
+        item_set.reduce_rule = item_set.reduce_rules.first
+      end
 
-      # If there is exactly one rule to reduce for this ItemSet, then do not
-      # figure out the lookaheads; just reduce it.
-      return reduce_rules.first if reduce_rules.size == 1
+      if item_set.reduce_rules.size > 1
+        # Force item_set.reduce_actions to be built to store the lookahead
+        # tokens for the possible reduce rules if there is more than one.
+        get_lookahead_reduce_actions_for_item_set(item_set)
+      end
+    end
 
-      # Otherwise, we have more than one possible rule to reduce.
+    # Get the reduce actions for a single item set (parser state).
+    #
+    # @param item_set [ItemSet]
+    #   ItemSet (parser state)
+    #
+    # @return [Hash]
+    #   Mapping of lookahead Tokens to the Rules to reduce.
+    def get_lookahead_reduce_actions_for_item_set(item_set)
+      item_set.reduce_actions ||= build_lookahead_reduce_actions_for_item_set(item_set)
+    end
 
+    # Build the reduce actions for a single item set (parser state).
+    #
+    # @param item_set [ItemSet]
+    #   ItemSet (parser state)
+    #
+    # @return [Hash]
+    #   Mapping of lookahead Tokens to the Rules to reduce.
+    def build_lookahead_reduce_actions_for_item_set(item_set)
       # We will be looking for all possible tokens that can follow instances of
       # these rules. Rather than looking through the entire grammar for the
       # possible following tokens, we will only look in the item sets leading
       # up to this one. This restriction gives us a more precise lookahead set,
       # and allows us to parse LALR grammars.
       item_sets = Set[item_set] + item_set.leading_item_sets
-      reduce_rules.reduce({}) do |reduce_actions, reduce_rule|
+      item_set.reduce_rules.reduce({}) do |reduce_actions, reduce_rule|
         lookahead_tokens_for_rule = build_lookahead_tokens_to_reduce(reduce_rule, item_sets)
         lookahead_tokens_for_rule.each do |lookahead_token|
           if existing_reduce_rule = reduce_actions[lookahead_token]
-            raise Error.new("Error: reduce/reduce conflict between rule #{existing_reduce_rule.id} (#{existing_reduce_rule.name}) and rule #{reduce_rule.id} (#{reduce_rule.name})")
+            raise Error.new("Error: reduce/reduce conflict (state #{item_set.id}) between rule #{existing_reduce_rule.name}##{existing_reduce_rule.id} (defined on line #{existing_reduce_rule.line_number}) and rule #{reduce_rule.name}##{reduce_rule.id} (defined on line #{reduce_rule.line_number})")
           end
           reduce_actions[lookahead_token] = reduce_rule
         end
@@ -183,9 +213,9 @@ class Propane
         # tokens to form the lookahead token set.
         item_sets.each do |item_set|
           item_set.items.each do |item|
-            if item.following_symbol == rule_set
+            if item.next_symbol == rule_set
               (1..).each do |offset|
-                case symbol = item.following_symbol(offset)
+                case symbol = item.next_symbol(offset)
                 when nil
                   rule_set = item.rule.rule_set
                   unless checked_rule_sets.include?(rule_set)
@@ -242,20 +272,26 @@ class Propane
         @log.puts
         @log.puts "  Incoming states: #{incoming_ids.join(", ")}"
         @log.puts "  Outgoing states:"
-        item_set.following_item_set.each do |following_symbol, following_item_set|
-          @log.puts "    #{following_symbol.name} => #{following_item_set.id}"
+        item_set.next_item_set.each do |next_symbol, next_item_set|
+          @log.puts "    #{next_symbol.name} => #{next_item_set.id}"
         end
         @log.puts
         @log.puts "  Reduce actions:"
-        case item_set.reduce_actions
-        when Rule
-          @log.puts "    * => rule #{item_set.reduce_actions.id}, rule set #{@rule_sets[item_set.reduce_actions.name].id} (#{item_set.reduce_actions.name})"
-        when Hash
+        if item_set.reduce_rule
+          @log.puts "    * => rule #{item_set.reduce_rule.id}, rule set #{@rule_sets[item_set.reduce_rule.name].id} (#{item_set.reduce_rule.name})"
+        elsif item_set.reduce_actions
           item_set.reduce_actions.each do |token, rule|
             @log.puts "    lookahead #{token.name} => #{rule.name} (#{rule.id}), rule set ##{rule.rule_set.id}"
           end
         end
       end
+      if @warnings.size > 0
+        @log.puts
+        @log.puts "Warnings:"
+        @warnings.each do |warning|
+          @log.puts "  #{warning}"
+        end
+      end
     end
 
   end

lib/propane/parser/item.rb

@@ -56,7 +56,7 @@ class Propane
 
       # Return the set of Items obtained by "closing" the current item.
       #
-      # If the following symbol for the current item is another Rule name, then
+      # If the next symbol for the current item is another Rule name, then
       # this method will return all Items for that Rule with a position of 0.
       # Otherwise, an empty Array is returned.
       #
@@ -81,17 +81,17 @@ class Propane
         @position == @rule.components.size
       end
 
-      # Get the following symbol for the Item.
+      # Get the next symbol for the Item.
       #
-      # That is, the symbol which follows the parse position marker in the
+      # That is, the symbol which is after the parse position marker in the
       # current Item.
       #
       # @param offset [Integer]
       #   Offset from current parse position to examine.
       #
       # @return [Token, RuleSet, nil]
-      #   Following symbol for the Item.
-      def following_symbol(offset = 0)
+      #   Next symbol for the Item.
+      def next_symbol(offset = 0)
         @rule.components[@position + offset]
       end
 
@@ -108,25 +108,25 @@ class Propane
         end
       end
 
-      # Get whether this Item is followed by the provided symbol.
+      # Get whether this Item's next symbol is the given symbol.
       #
       # @param symbol [Token, RuleSet]
       #   Symbol to query.
       #
       # @return [Boolean]
-      #   Whether this Item is followed by the provided symbol.
-      def followed_by?(symbol)
-        following_symbol == symbol
+      #   Whether this Item's next symbol is the given symbol.
+      def next_symbol?(symbol)
+        next_symbol == symbol
       end
 
-      # Get the following item for this Item.
+      # Get the next item for this Item.
       #
       # That is, the Item formed by moving the parse position marker one place
       # forward from its position in this Item.
       #
       # @return [Item]
-      #   The following item for this Item.
-      def following_item
+      #   The next item for this Item.
+      def next_item
         Item.new(@rule, @position + 1)
       end
 

lib/propane/parser/item_set.rb

@@ -2,7 +2,7 @@ class Propane
   class Parser
 
     # Represent a parser "item set", which is a set of possible items that the
-    # parser could currently be parsing.
+    # parser could currently be parsing. This is equivalent to a parser state.
     class ItemSet
 
       # @return [Set<Item>]
@@ -14,15 +14,24 @@ class Propane
       attr_accessor :id
 
       # @return [Hash]
-      #   Maps a following symbol to its ItemSet.
-      attr_reader :following_item_set
+      #   Maps a next symbol to its ItemSet.
+      attr_reader :next_item_set
 
       # @return [Set<ItemSet>]
       #   ItemSets leading to this item set.
       attr_reader :in_sets
 
-      # @return [nil, Rule, Hash]
-      #   Reduce actions, mapping lookahead tokens to rules.
+      # @return [nil, Rule]
+      #   Rule to reduce if there is only one possibility.
+      attr_accessor :reduce_rule
+
+      # @return [Set<Rule>]
+      #   Set of rules that could be reduced in this parser state.
+      attr_accessor :reduce_rules
+
+      # @return [nil, Hash]
+      #   Reduce actions, mapping lookahead tokens to rules, if there is
+      #   more than one rule that could be reduced.
       attr_accessor :reduce_actions
 
       # Build an ItemSet.
@@ -31,28 +40,28 @@ class Propane
       #   Items in this ItemSet.
       def initialize(items)
         @items = Set.new(items)
-        @following_item_set = {}
+        @next_item_set = {}
         @in_sets = Set.new
         close!
       end
 
-      # Get the set of following symbols for all Items in this ItemSet.
+      # Get the set of next symbols for all Items in this ItemSet.
       #
       # @return [Set<Token, RuleSet>]
-      #   Set of following symbols for all Items in this ItemSet.
-      def following_symbols
-        Set.new(@items.map(&:following_symbol).compact)
+      #   Set of next symbols for all Items in this ItemSet.
+      def next_symbols
+        @_next_symbols ||= Set.new(@items.map(&:next_symbol).compact)
       end
 
-      # Build a following ItemSet for the given following symbol.
+      # Build a next ItemSet for the given next symbol.
       #
       # @param symbol [Token, RuleSet]
-      #   Following symbol to build the following ItemSet for.
+      #   Next symbol to build the next ItemSet for.
       #
       # @return [ItemSet]
-      #   Following ItemSet for the given following symbol.
-      def build_following_item_set(symbol)
-        ItemSet.new(items_followed_by(symbol).map(&:following_item))
+      #   Next ItemSet for the given next symbol.
+      def build_next_item_set(symbol)
+        ItemSet.new(items_with_next(symbol).map(&:next_item))
       end
 
       # Hash function.
@@ -90,6 +99,8 @@ class Propane
       # @return [Set<ItemSet>]
       #   Set of all ItemSets that lead up to this ItemSet.
       def leading_item_sets
+        @_leading_item_sets ||=
+          begin
             result = Set.new
             eval_sets = Set[self]
             evaled = Set.new
@@ -106,6 +117,7 @@ class Propane
             end
             result
           end
+      end
 
       # Represent the ItemSet as a String.
       #
@@ -137,16 +149,16 @@ class Propane
         end
       end
 
-      # Get the Items followed by the given following symbol.
+      # Get the Items with the given next symbol.
       #
       # @param symbol [Token, RuleSet]
-      #   Following symbol.
+      #   Next symbol.
       #
       # @return [Array<Item>]
-      #   Items followed by the given following symbol.
-      def items_followed_by(symbol)
+      #   Items with the given next symbol.
+      def items_with_next(symbol)
         @items.select do |item|
-          item.followed_by?(symbol)
+          item.next_symbol?(symbol)
         end
       end
 

lib/propane/rule.rb

@@ -6,6 +6,10 @@ class Propane
     #   Rule components.
     attr_reader :components
 
+    # @return [Hash]
+    #   Field aliases.
+    attr_reader :aliases
+
     # @return [String]
     #   User code associated with the rule.
     attr_reader :code
@@ -49,7 +53,19 @@ class Propane
     #   Line number where the rule was defined in the input grammar.
     def initialize(name, components, code, ptypename, line_number)
       @name = name
-      @components = components
+      @aliases = {}
+      @components = components.each_with_index.map do |component, i|
+        if component =~ /(\S+):(\S+)/
+          c, aliasname = $1, $2
+          if @aliases[aliasname]
+            raise Error.new("Error: duplicate field alias `#{aliasname}` for rule #{name} defined on line #{line_number}")
+          end
+          @aliases[aliasname] = i
+          c
+        else
+          component
+        end
+      end
       @rule_set_node_field_index_map = components.map {0}
       @code = code
       @ptypename = ptypename

lib/propane/rule_set.rb

@@ -100,8 +100,10 @@ class Propane
 
     # Finalize a RuleSet after adding all Rules to it.
     def finalize(grammar)
+      if grammar.ast
         build_ast_fields(grammar)
       end
+    end
 
     private
 
@@ -148,6 +150,18 @@ class Propane
             "#{grammar.ast_prefix}#{node_name}#{grammar.ast_suffix}"
         end
       end
+      # Now merge in the field aliases as given by the user in the
+      # grammar.
+      field_aliases = {}
+      @rules.each do |rule|
+        rule.aliases.each do |alias_name, index|
+          if field_aliases[alias_name] && field_aliases[alias_name] != index
+            raise Error.new("Error: conflicting AST node field positions for alias `#{alias_name}`")
+          end
+          field_aliases[alias_name] = index
+          @ast_fields[index][alias_name] = @ast_fields[index].first[1]
+        end
+      end
     end
 
   end

lib/propane/version.rb

@@ -1,3 +1,3 @@
 class Propane
-  VERSION = "1.4.0"
+  VERSION = "1.5.1"
 end

spec/propane_spec.rb

@@ -54,6 +54,7 @@ EOF
     else
       command += %W[spec/run/testparser#{options[:name]}.propane spec/run/testparser#{options[:name]}.#{options[:language]} --log spec/run/testparser#{options[:name]}.log]
     end
+    command += (options[:extra_args] || [])
     if (options[:capture])
       stdout, stderr, status = Open3.capture3(*command)
       Results.new(stdout, stderr, status)
@@ -184,6 +185,70 @@ EOF
     expect(results.status).to_not eq 0
   end
 
+  it "warns on shift/reduce conflicts" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> As? b?;
+As -> a As2?;
+As2 -> b a As2?;
+EOF
+    results = run_propane(capture: true)
+    expect(results.stderr).to eq ""
+    expect(results.status).to eq 0
+    expect(File.binread("spec/run/testparser.log")).to match %r{Shift/Reduce conflict \(state \d+\) between token b and rule As2\? \(defined on line 4\)}
+  end
+
+  it "errors on shift/reduce conflicts with -w" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> As? b?;
+As -> a As2?;
+As2 -> b a As2?;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Shift/Reduce conflict \(state \d+\) between token b and rule As2\? \(defined on line 4\)}m
+    expect(results.status).to_not eq 0
+    expect(File.binread("spec/run/testparser.log")).to match %r{Shift/Reduce conflict \(state \d+\) between token b and rule As2\? \(defined on line 4\)}
+  end
+
+  it "errors on duplicate field aliases in a rule" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a:foo b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Error: duplicate field alias `foo` for rule Start defined on line 3}
+    expect(results.status).to_not eq 0
+  end
+
+  it "errors when an alias is in different positions for different rules in a rule set when AST mode is enabled" do
+    write_grammar <<EOF
+ast;
+token a;
+token b;
+Start -> a:foo b;
+Start -> b b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Error: conflicting AST node field positions for alias `foo`}
+    expect(results.status).to_not eq 0
+  end
+
+  it "does not error when an alias is in different positions for different rules in a rule set when AST mode is not enabled" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a:foo b;
+Start -> b b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to eq ""
+    expect(results.status).to eq 0
+  end
+
   %w[d c].each do |language|
 
     context "#{language.upcase} language" do
@@ -623,7 +688,7 @@ F -> e;
 EOF
         results = run_propane(capture: true, language: language)
         expect(results.status).to_not eq 0
-        expect(results.stderr).to match %r{reduce/reduce conflict.*\(E\).*\(F\)}
+        expect(results.stderr).to match %r{Error: reduce/reduce conflict \(state \d+\) between rule E#\d+ \(defined on line 10\) and rule F#\d+ \(defined on line 11\)}
       end
 
       it "provides matched text to user code blocks" do
@@ -1051,6 +1116,110 @@ EOF
         expect(results.stderr).to eq ""
         expect(results.status).to eq 0
       end
+
+      it "stores token and rule positions in AST nodes" do
+        write_grammar <<EOF
+ast;
+
+token a;
+token bb;
+token c /c(.|\\n)*c/;
+drop /\\s+/;
+Start -> T T T;
+T -> a;
+T -> bb;
+T -> c;
+EOF
+        run_propane(language: language)
+        compile("spec/test_ast_token_positions.#{language}", language: language)
+        results = run_test
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
+
+      it "stores invalid positions for empty rule matches" do
+        write_grammar <<EOF
+ast;
+
+token a;
+token bb;
+token c /c(.|\\n)*c/;
+drop /\\s+/;
+Start -> T Start;
+Start -> ;
+T -> a A;
+A -> bb? c?;
+EOF
+        run_propane(language: language)
+        compile("spec/test_ast_invalid_positions.#{language}", language: language)
+        results = run_test
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
+
+      it "allows specifying field aliases in AST mode" do
+        write_grammar <<EOF
+ast;
+
+token a;
+token b;
+token c;
+drop /\\s+/;
+Start -> T:first T:second T:third;
+T -> a;
+T -> b;
+T -> c;
+EOF
+        run_propane(language: language)
+        compile("spec/test_ast_field_aliases.#{language}", language: language)
+        results = run_test
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
+
+      it "allows specifying field aliases when AST mode is not enabled" do
+        if language == "d"
+          write_grammar <<EOF
+<<
+import std.stdio;
+>>
+ptype string;
+token id /[a-zA-Z_][a-zA-Z0-9_]*/ <<
+  $$ = match;
+>>
+drop /\\s+/;
+Start -> id:first id:second <<
+  writeln("first is ", ${first});
+  writeln("second is ", ${second});
+>>
+EOF
+        else
+          write_grammar <<EOF
+<<
+#include <stdio.h>
+#include <string.h>
+>>
+ptype char const *;
+token id /[a-zA-Z_][a-zA-Z0-9_]*/ <<
+  char * s = malloc(match_length + 1);
+  strncpy(s, (char const *)match, match_length);
+  s[match_length] = 0;
+  $$ = s;
+>>
+drop /\\s+/;
+Start -> id:first id:second <<
+  printf("first is %s\\n", ${first});
+  printf("second is %s\\n", ${second});
+>>
+EOF
+        end
+        run_propane(language: language)
+        compile("spec/test_field_aliases.#{language}", language: language)
+        results = run_test
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+        expect(results.stdout).to match /first is foo1.*second is bar2/m
+      end
     end
   end
 end

spec/test_ast_field_aliases.c

@@ -0,0 +1,19 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "\na\nb\nc";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(TOKEN_a, start->first->pToken->token);
+    assert_eq(TOKEN_b, start->second->pToken->token);
+    assert_eq(TOKEN_c, start->third->pToken->token);
+
+    return 0;
+}

spec/test_ast_field_aliases.d

@@ -0,0 +1,21 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "\na\nb\nc";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(TOKEN_a, start.first.pToken.token);
+    assert_eq(TOKEN_b, start.second.pToken.token);
+    assert_eq(TOKEN_c, start.third.pToken.token);
+}

spec/test_ast_invalid_positions.c

@@ -0,0 +1,102 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "\na\n  bb ccc";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(1, start->pT1->pToken->position.row);
+    assert_eq(0, start->pT1->pToken->position.col);
+    assert_eq(1, start->pT1->pToken->end_position.row);
+    assert_eq(0, start->pT1->pToken->end_position.col);
+    assert(p_position_valid(start->pT1->pA->position));
+    assert_eq(2, start->pT1->pA->position.row);
+    assert_eq(2, start->pT1->pA->position.col);
+    assert_eq(2, start->pT1->pA->end_position.row);
+    assert_eq(7, start->pT1->pA->end_position.col);
+    assert_eq(1, start->pT1->position.row);
+    assert_eq(0, start->pT1->position.col);
+    assert_eq(2, start->pT1->end_position.row);
+    assert_eq(7, start->pT1->end_position.col);
+
+    assert_eq(1, start->position.row);
+    assert_eq(0, start->position.col);
+    assert_eq(2, start->end_position.row);
+    assert_eq(7, start->end_position.col);
+
+    input = "a\nbb";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start->pT1->pToken->position.row);
+    assert_eq(0, start->pT1->pToken->position.col);
+    assert_eq(0, start->pT1->pToken->end_position.row);
+    assert_eq(0, start->pT1->pToken->end_position.col);
+    assert(p_position_valid(start->pT1->pA->position));
+    assert_eq(1, start->pT1->pA->position.row);
+    assert_eq(0, start->pT1->pA->position.col);
+    assert_eq(1, start->pT1->pA->end_position.row);
+    assert_eq(1, start->pT1->pA->end_position.col);
+    assert_eq(0, start->pT1->position.row);
+    assert_eq(0, start->pT1->position.col);
+    assert_eq(1, start->pT1->end_position.row);
+    assert_eq(1, start->pT1->end_position.col);
+
+    assert_eq(0, start->position.row);
+    assert_eq(0, start->position.col);
+    assert_eq(1, start->end_position.row);
+    assert_eq(1, start->end_position.col);
+
+    input = "a\nc\nc";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start->pT1->pToken->position.row);
+    assert_eq(0, start->pT1->pToken->position.col);
+    assert_eq(0, start->pT1->pToken->end_position.row);
+    assert_eq(0, start->pT1->pToken->end_position.col);
+    assert(p_position_valid(start->pT1->pA->position));
+    assert_eq(1, start->pT1->pA->position.row);
+    assert_eq(0, start->pT1->pA->position.col);
+    assert_eq(2, start->pT1->pA->end_position.row);
+    assert_eq(0, start->pT1->pA->end_position.col);
+    assert_eq(0, start->pT1->position.row);
+    assert_eq(0, start->pT1->position.col);
+    assert_eq(2, start->pT1->end_position.row);
+    assert_eq(0, start->pT1->end_position.col);
+
+    assert_eq(0, start->position.row);
+    assert_eq(0, start->position.col);
+    assert_eq(2, start->end_position.row);
+    assert_eq(0, start->end_position.col);
+
+    input = "a";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start->pT1->pToken->position.row);
+    assert_eq(0, start->pT1->pToken->position.col);
+    assert_eq(0, start->pT1->pToken->end_position.row);
+    assert_eq(0, start->pT1->pToken->end_position.col);
+    assert(!p_position_valid(start->pT1->pA->position));
+    assert_eq(0, start->pT1->position.row);
+    assert_eq(0, start->pT1->position.col);
+    assert_eq(0, start->pT1->end_position.row);
+    assert_eq(0, start->pT1->end_position.col);
+
+    assert_eq(0, start->position.row);
+    assert_eq(0, start->position.col);
+    assert_eq(0, start->end_position.row);
+    assert_eq(0, start->end_position.col);
+
+    return 0;
+}

spec/test_ast_invalid_positions.d

@@ -0,0 +1,104 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "\na\n  bb ccc";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(1, start.pT1.pToken.position.row);
+    assert_eq(0, start.pT1.pToken.position.col);
+    assert_eq(1, start.pT1.pToken.end_position.row);
+    assert_eq(0, start.pT1.pToken.end_position.col);
+    assert(start.pT1.pA.position.valid);
+    assert_eq(2, start.pT1.pA.position.row);
+    assert_eq(2, start.pT1.pA.position.col);
+    assert_eq(2, start.pT1.pA.end_position.row);
+    assert_eq(7, start.pT1.pA.end_position.col);
+    assert_eq(1, start.pT1.position.row);
+    assert_eq(0, start.pT1.position.col);
+    assert_eq(2, start.pT1.end_position.row);
+    assert_eq(7, start.pT1.end_position.col);
+
+    assert_eq(1, start.position.row);
+    assert_eq(0, start.position.col);
+    assert_eq(2, start.end_position.row);
+    assert_eq(7, start.end_position.col);
+
+    input = "a\nbb";
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start.pT1.pToken.position.row);
+    assert_eq(0, start.pT1.pToken.position.col);
+    assert_eq(0, start.pT1.pToken.end_position.row);
+    assert_eq(0, start.pT1.pToken.end_position.col);
+    assert(start.pT1.pA.position.valid);
+    assert_eq(1, start.pT1.pA.position.row);
+    assert_eq(0, start.pT1.pA.position.col);
+    assert_eq(1, start.pT1.pA.end_position.row);
+    assert_eq(1, start.pT1.pA.end_position.col);
+    assert_eq(0, start.pT1.position.row);
+    assert_eq(0, start.pT1.position.col);
+    assert_eq(1, start.pT1.end_position.row);
+    assert_eq(1, start.pT1.end_position.col);
+
+    assert_eq(0, start.position.row);
+    assert_eq(0, start.position.col);
+    assert_eq(1, start.end_position.row);
+    assert_eq(1, start.end_position.col);
+
+    input = "a\nc\nc";
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start.pT1.pToken.position.row);
+    assert_eq(0, start.pT1.pToken.position.col);
+    assert_eq(0, start.pT1.pToken.end_position.row);
+    assert_eq(0, start.pT1.pToken.end_position.col);
+    assert(start.pT1.pA.position.valid);
+    assert_eq(1, start.pT1.pA.position.row);
+    assert_eq(0, start.pT1.pA.position.col);
+    assert_eq(2, start.pT1.pA.end_position.row);
+    assert_eq(0, start.pT1.pA.end_position.col);
+    assert_eq(0, start.pT1.position.row);
+    assert_eq(0, start.pT1.position.col);
+    assert_eq(2, start.pT1.end_position.row);
+    assert_eq(0, start.pT1.end_position.col);
+
+    assert_eq(0, start.position.row);
+    assert_eq(0, start.position.col);
+    assert_eq(2, start.end_position.row);
+    assert_eq(0, start.end_position.col);
+
+    input = "a";
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(0, start.pT1.pToken.position.row);
+    assert_eq(0, start.pT1.pToken.position.col);
+    assert_eq(0, start.pT1.pToken.end_position.row);
+    assert_eq(0, start.pT1.pToken.end_position.col);
+    assert(!start.pT1.pA.position.valid);
+    assert_eq(0, start.pT1.position.row);
+    assert_eq(0, start.pT1.position.col);
+    assert_eq(0, start.pT1.end_position.row);
+    assert_eq(0, start.pT1.end_position.col);
+
+    assert_eq(0, start.position.row);
+    assert_eq(0, start.position.col);
+    assert_eq(0, start.end_position.row);
+    assert_eq(0, start.end_position.col);
+}

spec/test_ast_token_positions.c

@@ -0,0 +1,84 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "abbccc";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(0, start->pT1->pToken->position.row);
+    assert_eq(0, start->pT1->pToken->position.col);
+    assert_eq(0, start->pT1->pToken->end_position.row);
+    assert_eq(0, start->pT1->pToken->end_position.col);
+    assert_eq(0, start->pT1->position.row);
+    assert_eq(0, start->pT1->position.col);
+    assert_eq(0, start->pT1->end_position.row);
+    assert_eq(0, start->pT1->end_position.col);
+
+    assert_eq(0, start->pT2->pToken->position.row);
+    assert_eq(1, start->pT2->pToken->position.col);
+    assert_eq(0, start->pT2->pToken->end_position.row);
+    assert_eq(2, start->pT2->pToken->end_position.col);
+    assert_eq(0, start->pT2->position.row);
+    assert_eq(1, start->pT2->position.col);
+    assert_eq(0, start->pT2->end_position.row);
+    assert_eq(2, start->pT2->end_position.col);
+
+    assert_eq(0, start->pT3->pToken->position.row);
+    assert_eq(3, start->pT3->pToken->position.col);
+    assert_eq(0, start->pT3->pToken->end_position.row);
+    assert_eq(5, start->pT3->pToken->end_position.col);
+    assert_eq(0, start->pT3->position.row);
+    assert_eq(3, start->pT3->position.col);
+    assert_eq(0, start->pT3->end_position.row);
+    assert_eq(5, start->pT3->end_position.col);
+
+    assert_eq(0, start->position.row);
+    assert_eq(0, start->position.col);
+    assert_eq(0, start->end_position.row);
+    assert_eq(5, start->end_position.col);
+
+    input = "\n\n  bb\nc\ncc\n\n     a";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(2, start->pT1->pToken->position.row);
+    assert_eq(2, start->pT1->pToken->position.col);
+    assert_eq(2, start->pT1->pToken->end_position.row);
+    assert_eq(3, start->pT1->pToken->end_position.col);
+    assert_eq(2, start->pT1->position.row);
+    assert_eq(2, start->pT1->position.col);
+    assert_eq(2, start->pT1->end_position.row);
+    assert_eq(3, start->pT1->end_position.col);
+
+    assert_eq(3, start->pT2->pToken->position.row);
+    assert_eq(0, start->pT2->pToken->position.col);
+    assert_eq(4, start->pT2->pToken->end_position.row);
+    assert_eq(1, start->pT2->pToken->end_position.col);
+    assert_eq(3, start->pT2->position.row);
+    assert_eq(0, start->pT2->position.col);
+    assert_eq(4, start->pT2->end_position.row);
+    assert_eq(1, start->pT2->end_position.col);
+
+    assert_eq(6, start->pT3->pToken->position.row);
+    assert_eq(5, start->pT3->pToken->position.col);
+    assert_eq(6, start->pT3->pToken->end_position.row);
+    assert_eq(5, start->pT3->pToken->end_position.col);
+    assert_eq(6, start->pT3->position.row);
+    assert_eq(5, start->pT3->position.col);
+    assert_eq(6, start->pT3->end_position.row);
+    assert_eq(5, start->pT3->end_position.col);
+
+    assert_eq(2, start->position.row);
+    assert_eq(2, start->position.col);
+    assert_eq(6, start->end_position.row);
+    assert_eq(5, start->end_position.col);
+
+    return 0;
+}

spec/test_ast_token_positions.d

@@ -0,0 +1,86 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "abbccc";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(0, start.pT1.pToken.position.row);
+    assert_eq(0, start.pT1.pToken.position.col);
+    assert_eq(0, start.pT1.pToken.end_position.row);
+    assert_eq(0, start.pT1.pToken.end_position.col);
+    assert_eq(0, start.pT1.position.row);
+    assert_eq(0, start.pT1.position.col);
+    assert_eq(0, start.pT1.end_position.row);
+    assert_eq(0, start.pT1.end_position.col);
+
+    assert_eq(0, start.pT2.pToken.position.row);
+    assert_eq(1, start.pT2.pToken.position.col);
+    assert_eq(0, start.pT2.pToken.end_position.row);
+    assert_eq(2, start.pT2.pToken.end_position.col);
+    assert_eq(0, start.pT2.position.row);
+    assert_eq(1, start.pT2.position.col);
+    assert_eq(0, start.pT2.end_position.row);
+    assert_eq(2, start.pT2.end_position.col);
+
+    assert_eq(0, start.pT3.pToken.position.row);
+    assert_eq(3, start.pT3.pToken.position.col);
+    assert_eq(0, start.pT3.pToken.end_position.row);
+    assert_eq(5, start.pT3.pToken.end_position.col);
+    assert_eq(0, start.pT3.position.row);
+    assert_eq(3, start.pT3.position.col);
+    assert_eq(0, start.pT3.end_position.row);
+    assert_eq(5, start.pT3.end_position.col);
+
+    assert_eq(0, start.position.row);
+    assert_eq(0, start.position.col);
+    assert_eq(0, start.end_position.row);
+    assert_eq(5, start.end_position.col);
+
+    input = "\n\n  bb\nc\ncc\n\n     a";
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    start = p_result(&context);
+
+    assert_eq(2, start.pT1.pToken.position.row);
+    assert_eq(2, start.pT1.pToken.position.col);
+    assert_eq(2, start.pT1.pToken.end_position.row);
+    assert_eq(3, start.pT1.pToken.end_position.col);
+    assert_eq(2, start.pT1.position.row);
+    assert_eq(2, start.pT1.position.col);
+    assert_eq(2, start.pT1.end_position.row);
+    assert_eq(3, start.pT1.end_position.col);
+
+    assert_eq(3, start.pT2.pToken.position.row);
+    assert_eq(0, start.pT2.pToken.position.col);
+    assert_eq(4, start.pT2.pToken.end_position.row);
+    assert_eq(1, start.pT2.pToken.end_position.col);
+    assert_eq(3, start.pT2.position.row);
+    assert_eq(0, start.pT2.position.col);
+    assert_eq(4, start.pT2.end_position.row);
+    assert_eq(1, start.pT2.end_position.col);
+
+    assert_eq(6, start.pT3.pToken.position.row);
+    assert_eq(5, start.pT3.pToken.position.col);
+    assert_eq(6, start.pT3.pToken.end_position.row);
+    assert_eq(5, start.pT3.pToken.end_position.col);
+    assert_eq(6, start.pT3.position.row);
+    assert_eq(5, start.pT3.position.col);
+    assert_eq(6, start.pT3.end_position.row);
+    assert_eq(5, start.pT3.end_position.col);
+
+    assert_eq(2, start.position.row);
+    assert_eq(2, start.position.col);
+    assert_eq(6, start.end_position.row);
+    assert_eq(5, start.end_position.col);
+}

spec/test_field_aliases.c

@@ -0,0 +1,13 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "foo1\nbar2";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    return 0;
+}

spec/test_field_aliases.d

@@ -0,0 +1,15 @@
+import testparser;
+import std.stdio;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "foo1\nbar2";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+}

spec/test_lexer.c

@@ -43,41 +43,57 @@ int main()
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 0u);
     assert(token_info.position.col == 0u);
+    assert(token_info.end_position.row == 0u);
+    assert(token_info.end_position.col == 0u);
     assert(token_info.length == 1u);
     assert(token_info.token == TOKEN_int);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 0u);
     assert(token_info.position.col == 2u);
+    assert(token_info.end_position.row == 0u);
+    assert(token_info.end_position.col == 2u);
     assert(token_info.length == 1u);
     assert(token_info.token == TOKEN_plus);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 0u);
     assert(token_info.position.col == 4u);
+    assert(token_info.end_position.row == 0u);
+    assert(token_info.end_position.col == 4u);
     assert(token_info.length == 1u);
     assert(token_info.token == TOKEN_int);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 0u);
     assert(token_info.position.col == 6u);
+    assert(token_info.end_position.row == 0u);
+    assert(token_info.end_position.col == 6u);
     assert(token_info.length == 1u);
     assert(token_info.token == TOKEN_times);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 1u);
     assert(token_info.position.col == 0u);
+    assert(token_info.end_position.row == 1u);
+    assert(token_info.end_position.col == 2u);
     assert(token_info.length == 3u);
     assert(token_info.token == TOKEN_int);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 1u);
     assert(token_info.position.col == 4u);
+    assert(token_info.end_position.row == 1u);
+    assert(token_info.end_position.col == 4u);
     assert(token_info.length == 1u);
     assert(token_info.token == TOKEN_plus);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 1u);
     assert(token_info.position.col == 6u);
+    assert(token_info.end_position.row == 1u);
+    assert(token_info.end_position.col == 8u);
     assert(token_info.length == 3u);
     assert(token_info.token == TOKEN_int);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 1u);
     assert(token_info.position.col == 9u);
+    assert(token_info.end_position.row == 1u);
+    assert(token_info.end_position.col == 9u);
     assert(token_info.length == 0u);
     assert(token_info.token == TOKEN___EOF);
 
@@ -85,6 +101,8 @@ int main()
     assert(p_lex(&context, &token_info) == P_SUCCESS);
     assert(token_info.position.row == 0u);
     assert(token_info.position.col == 0u);
+    assert(token_info.end_position.row == 0u);
+    assert(token_info.end_position.col == 0u);
     assert(token_info.length == 0u);
     assert(token_info.token == TOKEN___EOF);
 

spec/test_lexer.d

@@ -47,23 +47,23 @@ unittest
     p_context_t context;
     p_context_init(&context, input);
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(0, 0), 1, TOKEN_int));
+    assert(token_info == p_token_info_t(p_position_t(0, 0), p_position_t(0, 0), 1, TOKEN_int));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(0, 2), 1, TOKEN_plus));
+    assert(token_info == p_token_info_t(p_position_t(0, 2), p_position_t(0, 2), 1, TOKEN_plus));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(0, 4), 1, TOKEN_int));
+    assert(token_info == p_token_info_t(p_position_t(0, 4), p_position_t(0, 4), 1, TOKEN_int));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(0, 6), 1, TOKEN_times));
+    assert(token_info == p_token_info_t(p_position_t(0, 6), p_position_t(0, 6), 1, TOKEN_times));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(1, 0), 3, TOKEN_int));
+    assert(token_info == p_token_info_t(p_position_t(1, 0), p_position_t(1, 2), 3, TOKEN_int));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(1, 4), 1, TOKEN_plus));
+    assert(token_info == p_token_info_t(p_position_t(1, 4), p_position_t(1, 4), 1, TOKEN_plus));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(1, 6), 3, TOKEN_int));
+    assert(token_info == p_token_info_t(p_position_t(1, 6), p_position_t(1, 8), 3, TOKEN_int));
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(1, 9), 0, TOKEN___EOF));
+    assert(token_info == p_token_info_t(p_position_t(1, 9), p_position_t(1, 9), 0, TOKEN___EOF));
 
     p_context_init(&context, "");
     assert(p_lex(&context, &token_info) == P_SUCCESS);
-    assert(token_info == p_token_info_t(p_position_t(0, 0), 0, TOKEN___EOF));
+    assert(token_info == p_token_info_t(p_position_t(0, 0), p_position_t(0, 0), 0, TOKEN___EOF));
 }