slang_preprocess.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

      *result = results[0];
   }
   else {
      /* The directive is dead. */
      *result = 0;
   }

   *pi += len + 1;
   return GL_TRUE;
}

#define ESCAPE_TOKEN 0

#define TOKEN_END       0
#define TOKEN_DEFINE    1
#define TOKEN_UNDEF     2
#define TOKEN_IF        3
#define TOKEN_ELSE      4
#define TOKEN_ELIF      5
#define TOKEN_ENDIF     6
#define TOKEN_ERROR     7
#define TOKEN_PRAGMA    8
#define TOKEN_EXTENSION 9
#define TOKEN_LINE      10

#define PARAM_END       0
#define PARAM_PARAMETER 1

#define BEHAVIOR_REQUIRE 1
#define BEHAVIOR_ENABLE  2
#define BEHAVIOR_WARN    3
#define BEHAVIOR_DISABLE 4

static GLboolean
preprocess_source (slang_string *output, const char *source, grammar pid, grammar eid,
                   slang_info_log *elog)
{
   static const char *predefined[] = {
      "__FILE__",
      "__LINE__",
      "__VERSION__",
#if FEATURE_es2_glsl
      "GL_ES",
      "GL_FRAGMENT_PRECISION_HIGH",
#endif
      NULL
   };
   byte *prod;
   GLuint size, i;
   pp_state state;

   if (!grammar_fast_check (pid, (const byte *) (source), &prod, &size, 65536)) {
      grammar_error_to_log (elog);
      return GL_FALSE;
   }

   pp_state_init (&state, elog);

   /* add the predefined symbols to the symbol table */
   for (i = 0; predefined[i]; i++) {
      pp_symbol *symbol = NULL;
      symbol = pp_symbols_push(&state.symbols);
      assert(symbol);
      slang_string_pushs(&symbol->name,
                         predefined[i], _mesa_strlen(predefined[i]));
   }

   i = 0;
   while (i < size) {
      if (prod[i] != ESCAPE_TOKEN) {
         if (state.cond.top->effective) {
            slang_string input;
            expand_state es;

            /* Eat only one line of source code to expand it.
             * FIXME: This approach has one drawback. If a macro with parameters spans across
             *        multiple lines, the preprocessor will raise an error. */
            slang_string_init (&input);
            while (prod[i] != '\0' && prod[i] != '\n')
               slang_string_pushc (&input, prod[i++]);
            if (prod[i] != '\0')
               slang_string_pushc (&input, prod[i++]);

            /* Increment line number. */
            state.line++;

            es.output = output;
            es.input = slang_string_cstr (&input);
            es.state = &state;
            if (!expand (&es, &state.symbols))
               goto error;

            slang_string_free (&input);
         }
         else {
            /* Condition stack is disabled - keep track on line numbers and output only newlines. */
            if (prod[i] == '\n') {
               state.line++;
               /*pp_annotate (output, "%c", prod[i]);*/
            }
            else {
               /*pp_annotate (output, "%c", prod[i]);*/
            }
            i++;
         }
      }
      else {
         const char *id;
         GLuint idlen;

         i++;
         switch (prod[i++]) {

         case TOKEN_END:
            /* End of source string.
               * Check if all #ifs have been terminated by matching #endifs.
               * On condition stack there should be only the global condition context. */
            if (state.cond.top->endif_required) {
               slang_info_log_error (elog, "end of source without matching #endif.");
               return GL_FALSE;
            }
            break;

         case TOKEN_DEFINE:
            {
               pp_symbol *symbol = NULL;

               /* Parse macro name. */
               id = (const char *) (&prod[i]);
               idlen = _mesa_strlen (id);
               if (state.cond.top->effective) {
                  pp_annotate (output, "// #define %s(", id);

                  /* If the symbol is already defined, override it. */
                  symbol = pp_symbols_find (&state.symbols, id);
                  if (symbol == NULL) {
                     symbol = pp_symbols_push (&state.symbols);
                     if (symbol == NULL)
                        goto error;
                     slang_string_pushs (&symbol->name, id, idlen);
                  }
                  else {
                     pp_symbol_reset (symbol);
                  }
               }
               i += idlen + 1;

               /* Parse optional macro parameters. */
               while (prod[i++] != PARAM_END) {
                  if (state.cond.top->effective) {
                     pp_symbol *param;

                     id = (const char *) (&prod[i]);
                     idlen = _mesa_strlen (id);
                     pp_annotate (output, "%s, ", id);
                     param = pp_symbols_push (&symbol->parameters);
                     if (param == NULL)
                        goto error;
                     slang_string_pushs (&param->name, id, idlen);
                  }
                  i += idlen + 1;
               }

               /* Parse macro replacement. */
               id = (const char *) (&prod[i]);
               idlen = _mesa_strlen (id);
               if (state.cond.top->effective) {
                  pp_annotate (output, ") %s", id);
                  slang_string_pushs (&symbol->replacement, id, idlen);
               }
               i += idlen + 1;
            }
            break;

         case TOKEN_UNDEF:
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;
            if (state.cond.top->effective) {
               pp_symbol *symbol;

               pp_annotate (output, "// #undef %s", id);
               /* Try to find symbol with given name and remove it. */
               symbol = pp_symbols_find (&state.symbols, id);
               if (symbol != NULL)
                  if (!pp_symbols_erase (&state.symbols, symbol))
                     goto error;
            }
            break;

         case TOKEN_IF:
            {
               GLint result;

               /* Parse #if expression end execute it. */
               pp_annotate (output, "// #if ");
               if (!parse_if (output, prod, &i, &result, &state, eid))
                  goto error;

               /* Push new condition on the stack. */
               if (!pp_cond_stack_push (&state.cond, state.elog))
                  goto error;
               state.cond.top->current = result ? GL_TRUE : GL_FALSE;
               state.cond.top->else_allowed = GL_TRUE;
               state.cond.top->endif_required = GL_TRUE;
               pp_cond_stack_reevaluate (&state.cond);
            }
            break;

         case TOKEN_ELSE:
            /* Check if #else is alloved here. */
            if (!state.cond.top->else_allowed) {
               slang_info_log_error (elog, "#else without matching #if.");
               goto error;
            }

            /* Negate current condition and reevaluate it. */
            state.cond.top->current = !state.cond.top->current;
            state.cond.top->else_allowed = GL_FALSE;
            pp_cond_stack_reevaluate (&state.cond);
            if (state.cond.top->effective)
               pp_annotate (output, "// #else");
            break;

         case TOKEN_ELIF:
            /* Check if #elif is alloved here. */
            if (!state.cond.top->else_allowed) {
               slang_info_log_error (elog, "#elif without matching #if.");
               goto error;
            }

            /* Negate current condition and reevaluate it. */
            state.cond.top->current = !state.cond.top->current;
            pp_cond_stack_reevaluate (&state.cond);

            if (state.cond.top->effective)
               pp_annotate (output, "// #elif ");

            {
               GLint result;

               /* Parse #elif expression end execute it. */
               if (!parse_if (output, prod, &i, &result, &state, eid))
                  goto error;

               /* Update current condition and reevaluate it. */
               state.cond.top->current = result ? GL_TRUE : GL_FALSE;
               pp_cond_stack_reevaluate (&state.cond);
            }
            break;

         case TOKEN_ENDIF:
            /* Check if #endif is alloved here. */
            if (!state.cond.top->endif_required) {
               slang_info_log_error (elog, "#endif without matching #if.");
               goto error;
            }

            /* Pop the condition off the stack. */
            state.cond.top++;
            if (state.cond.top->effective)
               pp_annotate (output, "// #endif");
            break;

         case TOKEN_EXTENSION:
            /* Parse the extension name. */
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;
            if (state.cond.top->effective)
               pp_annotate (output, "// #extension %s: ", id);

            /* Parse and apply extension behavior. */
            if (state.cond.top->effective) {
               switch (prod[i++]) {

               case BEHAVIOR_REQUIRE:
                  pp_annotate (output, "require");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        slang_info_log_error (elog, "require: bad behavior for #extension all.");
                        goto error;
                     }
                     else {
                        slang_info_log_error (elog, "%s: required extension is not supported.", id);
                        goto error;
                     }
                  }
                  break;

               case BEHAVIOR_ENABLE:
                  pp_annotate (output, "enable");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        slang_info_log_error (elog, "enable: bad behavior for #extension all.");
                        goto error;
                     }
                     else {
                        slang_info_log_warning (elog, "%s: enabled extension is not supported.", id);
                     }
                  }
                  break;

               case BEHAVIOR_WARN:
                  pp_annotate (output, "warn");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") != 0) {
                        slang_info_log_warning (elog, "%s: enabled extension is not supported.", id);
                     }
                  }
                  break;

               case BEHAVIOR_DISABLE:
                  pp_annotate (output, "disable");
                  if (!pp_ext_set (&state.ext, id, GL_FALSE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        pp_ext_disable_all (&state.ext);
                     }
                     else {
                        slang_info_log_warning (elog, "%s: disabled extension is not supported.", id);
                     }
                  }
                  break;

               default:
                  assert (0);
               }
            }
            break;

         case TOKEN_LINE:
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;

            if (state.cond.top->effective) {
               slang_string buffer;
               GLuint count;
               GLint results[2];
               expand_state es;

               slang_string_init (&buffer);
               state.line++;
               es.output = &buffer;
               es.input = id;
               es.state = &state;
               if (!expand (&es, &state.symbols))
                  goto error;

               pp_annotate (output, "// #line ");
               count = execute_expressions (output, eid,
                                             (const byte *) (slang_string_cstr (&buffer)),
                                             results, state.elog);
               slang_string_free (&buffer);
               if (count == 0)
                  goto error;

               state.line = results[0] - 1;
               if (count == 2)
                  state.file = results[1];
            }
            break;
         }
      }
   }

   /* Check for missing #endifs. */
   if (state.cond.top->endif_required) {
      slang_info_log_error (elog, "#endif expected but end of source found.");
      goto error;
   }

   grammar_alloc_free(prod);
   pp_state_free (&state);
   return GL_TRUE;

error:
   grammar_alloc_free(prod);
   pp_state_free (&state);
   return GL_FALSE;
}

GLboolean
_slang_preprocess_directives (slang_string *output, const char *input, slang_info_log *elog)
{
   grammar pid, eid;
   GLboolean success;

   pid = grammar_load_from_text ((const byte *) (slang_pp_directives_syn));
   if (pid == 0) {
      grammar_error_to_log (elog);
      return GL_FALSE;
   }
   eid = grammar_load_from_text ((const byte *) (slang_pp_expression_syn));
   if (eid == 0) {
      grammar_error_to_log (elog);
      grammar_destroy (pid);
      return GL_FALSE;
   }
   success = preprocess_source (output, input, pid, eid, elog);
   grammar_destroy (eid);
   grammar_destroy (pid);
   return success;
}