Add token_names API - close #17

assets/parser.c.erb

@@ -3,6 +3,17 @@
 #include <stdlib.h>
 #include <string.h>
 
+/**************************************************************************
+ * Public data
+ *************************************************************************/
+
+/** Token names. */
+const char * <%= @grammar.prefix %>token_names[] = {
+<% @grammar.tokens.each_with_index do |token, index| %>
+    "<%= token.name %>",
+<% end %>
+};
+
 /**************************************************************************
  * User code blocks
  *************************************************************************/

assets/parser.h.erb

@@ -116,6 +116,13 @@ typedef struct
     size_t user_terminate_code;
 } <%= @grammar.prefix %>context_t;
 
+/**************************************************************************
+ * Public data
+ *************************************************************************/
+
+/** Token names. */
+extern const char * <%= @grammar.prefix %>token_names[];
+
 void <%= @grammar.prefix %>context_init(<%= @grammar.prefix %>context_t * context, uint8_t const * input, size_t input_length);
 
 size_t <%= @grammar.prefix %>decode_code_point(uint8_t const * input, size_t input_length,

doc/user_guide.md

@@ -726,6 +726,28 @@ if (p_parse(&context) == P_USER_TERMINATED)
 }
 ```
 
+##> Data
+
+### `p_token_names`
+
+The `p_token_names` array contains the grammar-specified token names.
+It is indexed by the token ID.
+
+C example:
+
+```
+p_context_t context;
+p_context_init(&context, input, input_length);
+size_t result = p_parse(&context);
+if (p_parse(&context) == P_UNEXPECTED_TOKEN)
+{
+    p_position_t error_position = p_position(&context);
+    fprintf(stderr, "Error: unexpected token `%s' at row %u column %u\n",
+        p_token_names[context.token],
+        error_position.row + 1, error_position.col + 1);
+}
+```
+
 #> License
 
 Propane is licensed under the terms of the MIT License:

spec/test_error_positions.c

@@ -35,5 +35,8 @@ int main()
     assert(p_position(&context).row == 5);
     assert(p_position(&context).col == 4);
 
+    assert(strcmp(p_token_names[TOKEN_a], "a") == 0);
+    assert(strcmp(p_token_names[TOKEN_num], "num") == 0);
+
     return 0;
 }

spec/test_error_positions.d

@@ -34,4 +34,7 @@ unittest
     p_context_init(&context, input);
     assert(p_parse(&context) == P_DECODE_ERROR);
     assert(p_position(&context) == p_position_t(5, 4));
+
+    assert(p_token_names[TOKEN_a] == "a");
+    assert(p_token_names[TOKEN_num] == "num");
 }