Track rule component positions - close #41

assets/parser.c.erb

@@ -711,6 +711,8 @@ typedef struct
     /** tree node. */
     void * tree_node;
 <% else %>
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
     /** Parser value from this state. */
     <%= @grammar.prefix %>value_t pvalue;
 <% end %>
@@ -866,6 +868,57 @@ static void state_values_stack_free(state_values_stack_t * stack)
 }
 
 <% unless @grammar.tree %>
+/**
+ * Get the rule position (start or end) for the currently matched rule.
+ */
+static <%= @grammar.prefix %>position_t get_rule_position(state_values_stack_t * statevalues, size_t i, size_t n_states, bool get_end)
+{
+    if (n_states > 0u)
+    {
+        if (i == 0u)
+        {
+            if (get_end)
+            {
+                int stack_index = -1;
+                for (size_t j = 0u; j < n_states; j++)
+                {
+                    state_value_t * sv = state_values_stack_index(statevalues, stack_index - (int)j);
+                    if (<%= @grammar.prefix %>position_valid(sv->end_position))
+                    {
+                        return sv->end_position;
+                    }
+                }
+            }
+            else
+            {
+                int stack_index = -(int)n_states;
+                for (size_t j = 0u; j < n_states; j++)
+                {
+                    state_value_t * sv = state_values_stack_index(statevalues, stack_index + (int)j);
+                    if (<%= @grammar.prefix %>position_valid(sv->position))
+                    {
+                        return sv->position;
+                    }
+                }
+            }
+        }
+        else
+        {
+            if (get_end)
+            {
+                return state_values_stack_index(statevalues, -1 - (int)n_states + (int)i)->end_position;
+            }
+            else
+            {
+                return state_values_stack_index(statevalues, -1 - (int)n_states + (int)i)->position;
+            }
+        }
+    }
+    <%= @grammar.prefix %>position_t empty_pos;
+    memset(&empty_pos, 0, sizeof(empty_pos));
+    return empty_pos;
+}
+
 /**
  * Execute user code associated with a parser rule.
  *
@@ -971,6 +1024,8 @@ static size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t start
 <% if @grammar.tree %>
     void * reduced_parser_node;
 <% else %>
+    <%= @grammar.prefix %>position_t reduced_position;
+    <%= @grammar.prefix %>position_t reduced_end_position;
     <%= @grammar.prefix %>value_t reduced_parser_value;
 <% end %>
     state_values_stack_init(&statevalues);
@@ -1013,7 +1068,8 @@ static size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t start
         {
             /* We have something to shift. */
             state_values_stack_push(&statevalues);
-            state_values_stack_index(&statevalues, -1)->state_id = shift_state;
+            state_value_t * new_state_info = state_values_stack_index(&statevalues, -1);
+            new_state_info->state_id = shift_state;
             if (reduced_rule_set == INVALID_ID)
             {
                 /* We shifted a token, mark it consumed. */
@@ -1030,9 +1086,11 @@ static size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t start
                 token_tree_node->token = token;
                 token_tree_node->pvalue = token_info.pvalue;
 <%= expand_code(@grammar.on_token_node, false, nil, nil) %>
-                state_values_stack_index(&statevalues, -1)->tree_node = token_tree_node;
+                new_state_info->tree_node = token_tree_node;
 <% else %>
-                state_values_stack_index(&statevalues, -1)->pvalue = token_info.pvalue;
+                new_state_info->position = token_info.position;
+                new_state_info->end_position = token_info.end_position;
+                new_state_info->pvalue = token_info.pvalue;
 <% end %>
                 token = INVALID_TOKEN_ID;
             }
@@ -1040,9 +1098,11 @@ static size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t start
             {
                 /* We shifted a RuleSet. */
 <% if @grammar.tree %>
-                state_values_stack_index(&statevalues, -1)->tree_node = reduced_parser_node;
+                new_state_info->tree_node = reduced_parser_node;
 <% else %>
-                state_values_stack_index(&statevalues, -1)->pvalue = reduced_parser_value;
+                new_state_info->pvalue = reduced_parser_value;
+                new_state_info->position = reduced_position;
+                new_state_info->end_position = reduced_end_position;
                 <%= @grammar.prefix %>value_t new_parse_result;
                 memset(&new_parse_result, 0, sizeof(new_parse_result));
                 reduced_parser_value = new_parse_result;
@@ -1113,6 +1173,16 @@ static size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t start
                 return P_USER_TERMINATED;
             }
             reduced_parser_value = reduced_parser_value2;
+            if (parser_reduce_table[reduce_index].n_states > 0u)
+            {
+                reduced_position = get_rule_position(&statevalues, 0u, parser_reduce_table[reduce_index].n_states, false);
+                reduced_end_position = get_rule_position(&statevalues, 0u, parser_reduce_table[reduce_index].n_states, true);
+            }
+            else
+            {
+                memset(&reduced_position, 0, sizeof(reduced_position));
+                memset(&reduced_end_position, 0, sizeof(reduced_end_position));
+            }
 <% end %>
             reduced_rule_set = parser_reduce_table[reduce_index].rule_set;
             state_values_stack_pop(&statevalues, parser_reduce_table[reduce_index].n_states);

assets/parser.d.erb

@@ -886,6 +886,8 @@ private struct state_value_t
     /** Tree node. */
     void * tree_node;
 <% else %>
+    <%= @grammar.prefix %>position_t position;
+    <%= @grammar.prefix %>position_t end_position;
     /** Parser value from this state. */
     <%= @grammar.prefix %>value_t pvalue;
 <% end %>
@@ -941,6 +943,53 @@ private immutable parser_state_t[] parser_state_table = [
 ];
 
 <% unless @grammar.tree %>
+/**
+ * Get the rule position (start or end) for the currently matched rule.
+ */
+private <%= @grammar.prefix %>position_t get_rule_position(state_value_t[] statevalues, size_t i, size_t n_states, bool get_end)
+{
+    if (n_states > 0u)
+    {
+        if (i == 0u)
+        {
+            if (get_end)
+            {
+                for (size_t j = 0u; j < n_states; j++)
+                {
+                    state_value_t * sv = &statevalues[$-1-j];
+                    if (sv.end_position.valid)
+                    {
+                        return sv.end_position;
+                    }
+                }
+            }
+            else
+            {
+                for (size_t j = 0u; j < n_states; j++)
+                {
+                    state_value_t * sv = &statevalues[$-n_states+j];
+                    if (sv.position.valid)
+                    {
+                        return sv.position;
+                    }
+                }
+            }
+        }
+        else
+        {
+            if (get_end)
+            {
+                return statevalues[$-1-n_states+i].end_position;
+            }
+            else
+            {
+                return statevalues[$-1-n_states+i].position;
+            }
+        }
+    }
+    return <%= @grammar.prefix %>position_t.INVALID;
+}
+
 /**
  * Execute user code associated with a parser rule.
  *
@@ -1047,6 +1096,8 @@ private size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t star
 <% if @grammar.tree %>
     void * reduced_parser_node;
 <% else %>
+    <%= @grammar.prefix %>position_t reduced_position;
+    <%= @grammar.prefix %>position_t reduced_end_position;
     <%= @grammar.prefix %>value_t reduced_parser_value;
 <% end %>
     for (;;)
@@ -1091,6 +1142,8 @@ private size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t star
 <%= expand_code(@grammar.on_token_node, false, nil, nil) %>
                 statevalues[$-1].tree_node = token_tree_node;
 <% else %>
+                statevalues[$-1].position = token_info.position;
+                statevalues[$-1].end_position = token_info.end_position;
                 statevalues[$-1].pvalue = token_info.pvalue;
 <% end %>
                 token = INVALID_TOKEN_ID;
@@ -1102,6 +1155,8 @@ private size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t star
                 statevalues[$-1].tree_node = reduced_parser_node;
 <% else %>
                 statevalues[$-1].pvalue = reduced_parser_value;
+                statevalues[$-1].position = reduced_position;
+                statevalues[$-1].end_position = reduced_end_position;
                 <%= @grammar.prefix %>value_t new_parse_result;
                 reduced_parser_value = new_parse_result;
 <% end %>
@@ -1174,6 +1229,16 @@ private size_t parse_from(<%= @grammar.prefix %>context_t * context, size_t star
                 return P_USER_TERMINATED;
             }
             reduced_parser_value = reduced_parser_value2;
+            if (parser_reduce_table[reduce_index].n_states > 0u)
+            {
+                reduced_position = get_rule_position(statevalues, 0u, parser_reduce_table[reduce_index].n_states, false);
+                reduced_end_position = get_rule_position(statevalues, 0u, parser_reduce_table[reduce_index].n_states, true);
+            }
+            else
+            {
+                reduced_position = <%= @grammar.prefix %>position_t.INVALID;
+                reduced_end_position = <%= @grammar.prefix %>position_t.INVALID;
+            }
 <% end %>
             reduced_rule_set = parser_reduce_table[reduce_index].rule_set;
             statevalues.length -= parser_reduce_table[reduce_index].n_states;

doc/user_guide.md

@@ -217,6 +217,41 @@ rule.
 Parser values for the rules or tokens in the rule pattern can be accessed
 positionally with tokens `$1`, `$2`, `$3`, etc...
 
+The input text positions for the reduced rule and for the individual rule
+components can also be accessed from within a parser rule code block.
+Each of these positions is an instance of the `p_position_t` structure (see
+`${#p_position_t}`), which contains 1-based `row` and `col` fields.
+
+The start position of the overall reduced rule is accessed with
+`${$.position}`, and the end position of the overall reduced rule is accessed
+with `${$.end_position}`.
+
+The start and end positions of an individual rule component are accessed
+positionally with `${N.position}` and `${N.end_position}`, where `N` is the
+1-based index of the component (`${1.position}` for the first component,
+`${2.position}` for the second, and so on).
+
+Example:
+
+```
+Assignment -> ident equals Expr <<
+    printf("assignment on row %d, col %d\n",
+        ${$.position}.row, ${$.position}.col);
+    printf("target identifier ends on row %d, col %d\n",
+        ${1.end_position}.row, ${1.end_position}.col);
+    printf("expression starts on row %d, col %d\n",
+        ${3.position}.row, ${3.position}.col);
+>>
+```
+
+A rule or rule component that allows for an empty match may not have valid
+positions.
+In this case the position should be checked for validity before its `row` and
+`col` fields are used (see `${#p_position_valid}`).
+For C targets this can be accomplished with
+`if (p_position_valid(${$.position}))` and for D targets this can be
+accomplished with `if (${$.position}.valid)`.
+
 Parser rule code blocks are not available in tree generation mode.
 In tree generation mode, a full parse tree is automatically constructed in
 memory for user code to traverse after parsing is complete.

lib/propane/generator.rb

@@ -312,6 +312,14 @@ class Propane
             "statevalues[$-1-n_states+#{index}].pvalue.v_#{rule.components[index - 1].ptypename}"
           end
         end
+        code = code.gsub(/\$\{(\$|\d+)\.position\}/) do |match|
+          index = $1.to_i
+          "get_rule_position(statevalues, #{index}, n_states, false)"
+        end
+        code = code.gsub(/\$\{(\$|\d+)\.end_position\}/) do |match|
+          index = $1.to_i
+          "get_rule_position(statevalues, #{index}, n_states, true)"
+        end
         code = code.gsub(/\$\{(\w+)\}/) do |match|
           aliasname = $1
           if index = rule.aliases[aliasname]

spec/propane_spec.rb

@@ -1814,6 +1814,132 @@ EOF
         expect(results.stderr).to eq ""
         expect(results.status).to eq 0
       end
+
+      it "allows accessing rule and component text positions" do
+        if language == "d"
+          write_grammar <<EOF
+<<
+import std.stdio;
+>>
+drop /\\s+/;
+token tok1;
+token tok2;
+token ident /[a-zA-Z_]\\w*/;
+token num /\\d+/;
+Num -> num;
+Start -> ident Num <<
+    writeln("ident start: ", ${1.position}.row, ", ", ${1.position}.col);
+    writeln("ident end: ", ${1.end_position}.row, ", ", ${1.end_position}.col);
+    writeln("Num start: ", ${2.position}.row, ", ", ${2.position}.col);
+    writeln("Num end: ", ${2.end_position}.row, ", ", ${2.end_position}.col);
+    writeln("Start start: ", ${$.position}.row, ", ", ${$.position}.col);
+    writeln("Start end: ", ${$.end_position}.row, ", ", ${$.end_position}.col);
+>>
+R -> Empty tok2 <<
+    writeln("Empty start: ", ${1.position}.row, ", ", ${1.position}.col);
+    writeln("Empty end: ", ${1.end_position}.row, ", ", ${1.end_position}.col);
+    writeln("tok2 start: ", ${2.position}.row, ", ", ${2.position}.col);
+    writeln("tok2 end: ", ${2.end_position}.row, ", ", ${2.end_position}.col);
+    writeln("R start: ", ${$.position}.row, ", ", ${$.position}.col);
+    writeln("R end: ", ${$.end_position}.row, ", ", ${$.end_position}.col);
+>>
+R -> tok1 Empty <<
+    writeln("tok1 start: ", ${1.position}.row, ", ", ${1.position}.col);
+    writeln("tok1 end: ", ${1.end_position}.row, ", ", ${1.end_position}.col);
+    writeln("Empty start: ", ${2.position}.row, ", ", ${2.position}.col);
+    writeln("Empty end: ", ${2.end_position}.row, ", ", ${2.end_position}.col);
+    writeln("R2 start: ", ${$.position}.row, ", ", ${$.position}.col);
+    writeln("R2 end: ", ${$.end_position}.row, ", ", ${$.end_position}.col);
+>>
+Empty -> ;
+Start -> R <<
+    writeln("StartR start: ", ${$.position}.row, ", ", ${$.position}.col);
+    writeln("StartR end: ", ${$.end_position}.row, ", ", ${$.end_position}.col);
+>>
+Start -> Empty <<
+    writeln("StartEmpty start: ", ${$.position}.row, ", ", ${$.position}.col);
+    writeln("StartEmpty end: ", ${$.end_position}.row, ", ", ${$.end_position}.col);
+>>
+EOF
+        else
+          write_grammar <<EOF
+<<
+#include <stdio.h>
+>>
+drop /\\s+/;
+token tok1;
+token tok2;
+token ident /[a-zA-Z_]\\w*/;
+token num /\\d+/;
+Num -> num;
+token pct /%/;
+Start -> ident Num <<
+    printf("ident start: %d, %d\\n", ${1.position}.row, ${1.position}.col);
+    printf("ident end: %d, %d\\n", ${1.end_position}.row, ${1.end_position}.col);
+    printf("Num start: %d, %d\\n", ${2.position}.row, ${2.position}.col);
+    printf("Num end: %d, %d\\n", ${2.end_position}.row, ${2.end_position}.col);
+    printf("Start start: %d, %d\\n", ${$.position}.row, ${$.position}.col);
+    printf("Start end: %d, %d\\n", ${$.end_position}.row, ${$.end_position}.col);
+>>
+R -> Empty tok2 <<
+    printf("Empty start: %d, %d\\n", ${1.position}.row, ${1.position}.col);
+    printf("Empty end: %d, %d\\n", ${1.end_position}.row, ${1.end_position}.col);
+    printf("tok2 start: %d, %d\\n", ${2.position}.row, ${2.position}.col);
+    printf("tok2 end: %d, %d\\n", ${2.end_position}.row, ${2.end_position}.col);
+    printf("R start: %d, %d\\n", ${$.position}.row, ${$.position}.col);
+    printf("R end: %d, %d\\n", ${$.end_position}.row, ${$.end_position}.col);
+>>
+R -> tok1 Empty <<
+    printf("tok1 start: %d, %d\\n", ${1.position}.row, ${1.position}.col);
+    printf("tok1 end: %d, %d\\n", ${1.end_position}.row, ${1.end_position}.col);
+    printf("Empty start: %d, %d\\n", ${2.position}.row, ${2.position}.col);
+    printf("Empty end: %d, %d\\n", ${2.end_position}.row, ${2.end_position}.col);
+    printf("R2 start: %d, %d\\n", ${$.position}.row, ${$.position}.col);
+    printf("R2 end: %d, %d\\n", ${$.end_position}.row, ${$.end_position}.col);
+>>
+Empty -> ;
+Start -> R <<
+    printf("StartR start: %d, %d\\n", ${$.position}.row, ${$.position}.col);
+    printf("StartR end: %d, %d\\n", ${$.end_position}.row, ${$.end_position}.col);
+>>
+Start -> Empty <<
+    printf("StartEmpty start: %d, %d\\n", ${$.position}.row, ${$.position}.col);
+    printf("StartEmpty end: %d, %d\\n", ${$.end_position}.row, ${$.end_position}.col);
+>>
+EOF
+        end
+        run_propane(language: language)
+        compile("spec/test_positions.#{language}", language: language)
+        results = run_test(language: language)
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+        expect(results.stdout).to eq <<EOF
+ident start: 1, 5
+ident end: 1, 9
+Num start: 3, 9
+Num end: 3, 12
+Start start: 1, 5
+Start end: 3, 12
+
+Empty start: 0, 0
+Empty end: 0, 0
+tok2 start: 2, 2
+tok2 end: 2, 5
+R start: 2, 2
+R end: 2, 5
+StartR start: 2, 2
+StartR end: 2, 5
+
+tok1 start: 1, 3
+tok1 end: 1, 6
+Empty start: 0, 0
+Empty end: 0, 0
+R2 start: 1, 3
+R2 end: 1, 6
+StartR start: 1, 3
+StartR end: 1, 6
+EOF
+      end
     end
   end
 end

spec/test_positions.c

@@ -0,0 +1,29 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+
+int main()
+{
+    char const * input = "    Hello\n\n        4200\n";
+    p_context_t * context;
+    context = p_context_new((uint8_t const *)input, strlen(input));
+    assert(p_parse(context) == P_SUCCESS);
+    p_context_delete(context);
+
+    printf("\n");
+
+    input = "\n tok2";
+    context = p_context_new((uint8_t const *)input, strlen(input));
+    assert(p_parse(context) == P_SUCCESS);
+    p_context_delete(context);
+
+    printf("\n");
+
+    input = "  tok1";
+    context = p_context_new((uint8_t const *)input, strlen(input));
+    assert(p_parse(context) == P_SUCCESS);
+    p_context_delete(context);
+
+    return 0;
+}

spec/test_positions.d

@@ -0,0 +1,27 @@
+import testparser;
+import std.stdio;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "    Hello\n\n        4200\n";
+    p_context_t * context;
+    context = p_context_new(input);
+    assert(p_parse(context) == P_SUCCESS);
+
+    writeln();
+
+    input = "\n tok2";
+    context = p_context_new(input);
+    assert(p_parse(context) == P_SUCCESS);
+
+    writeln();
+
+    input = "  tok1";
+    context = p_context_new(input);
+    assert(p_parse(context) == P_SUCCESS);
+}