slang_preprocess.c

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

   return &self->symbols[self->count++];
}

static GLboolean
pp_symbols_erase (pp_symbols *self, pp_symbol *symbol)
{
   assert (symbol >= self->symbols && symbol < self->symbols + self->count);

   self->count--;
   pp_symbol_free (symbol);
   if (symbol < self->symbols + self->count)
      _mesa_memcpy (symbol, symbol + 1, sizeof (pp_symbol) * (self->symbols + self->count - symbol));
   self->symbols = (pp_symbol *) (_mesa_realloc (self->symbols, (self->count + 1) * sizeof (pp_symbol),
                                                 self->count * sizeof (pp_symbol)));
   return self->symbols != NULL;
}

static pp_symbol *
pp_symbols_find (pp_symbols *self, const char *name)
{
   GLuint i;

   for (i = 0; i < self->count; i++)
      if (_mesa_strcmp (name, slang_string_cstr (&self->symbols[i].name)) == 0)
         return &self->symbols[i];
   return NULL;
}

/*
 * The condition context of a single #if/#else/#endif level. Those can be nested, so there
 * is a stack of condition contexts.
 * There is a special global context on the bottom of the stack. It is there to simplify
 * context handling.
 */

typedef struct
{
   GLboolean current;         /* The condition value of this level. */
   GLboolean effective;       /* The effective product of current condition, outer level conditions
                               * and position within #if-#else-#endif sections. */
   GLboolean else_allowed;    /* TRUE if in #if-#else section, FALSE if in #else-#endif section
                               * and for global context. */
   GLboolean endif_required;  /* FALSE for global context only. */
} pp_cond_ctx;

/* Should be enuff. */
#define CONDITION_STACK_SIZE 64

typedef struct
{
   pp_cond_ctx stack[CONDITION_STACK_SIZE];
   pp_cond_ctx *top;
} pp_cond_stack;

static GLboolean
pp_cond_stack_push (pp_cond_stack *self, slang_info_log *elog)
{
   if (self->top == self->stack) {
      slang_info_log_error (elog, "internal compiler error: preprocessor condition stack overflow.");
      return GL_FALSE;
   }
   self->top--;
   return GL_TRUE;
}

static GLvoid
pp_cond_stack_reevaluate (pp_cond_stack *self)
{
   /* There must be at least 2 conditions on the stack - one global and one being evaluated. */
   assert (self->top <= &self->stack[CONDITION_STACK_SIZE - 2]);

   self->top->effective = self->top->current && self->top[1].effective;
}

/*
 * Extension enables through #extension directive.
 * NOTE: Currently, only enable/disable state is stored.
 */

typedef struct
{
   GLboolean MESA_shader_debug;        /* GL_MESA_shader_debug enable */
   GLboolean ARB_texture_rectangle; /* GL_ARB_texture_rectangle enable */
} pp_ext;

/*
 * Disable all extensions. Called at startup and on #extension all: disable.
 */
static GLvoid
pp_ext_disable_all (pp_ext *self)
{
   self->MESA_shader_debug = GL_FALSE;
}

static GLvoid
pp_ext_init (pp_ext *self)
{
   pp_ext_disable_all (self);
   self->ARB_texture_rectangle = GL_TRUE;
   /* Other initialization code goes here. */
}

static GLboolean
pp_ext_set (pp_ext *self, const char *name, GLboolean enable)
{
   if (_mesa_strcmp (name, "MESA_shader_debug") == 0)
      self->MESA_shader_debug = enable;
   else if (_mesa_strcmp (name, "GL_ARB_texture_rectangle") == 0)
      self->ARB_texture_rectangle = enable;
   /* Next extension name tests go here. */
   else
      return GL_FALSE;
   return GL_TRUE;
}

/*
 * The state of preprocessor: current line, file and version number, list of all defined macros
 * and the #if/#endif context.
 */

typedef struct
{
   GLint line;
   GLint file;
   GLint version;
   pp_symbols symbols;
   pp_ext ext;
   slang_info_log *elog;
   pp_cond_stack cond;
} pp_state;

static GLvoid
pp_state_init (pp_state *self, slang_info_log *elog)
{
   self->line = 0;
   self->file = 1;
#if FEATURE_es2_glsl
   self->version = 100;
#else
   self->version = 110;
#endif
   pp_symbols_init (&self->symbols);
   pp_ext_init (&self->ext);
   self->elog = elog;

   /* Initialize condition stack and create the global context. */
   self->cond.top = &self->cond.stack[CONDITION_STACK_SIZE - 1];
   self->cond.top->current = GL_TRUE;
   self->cond.top->effective = GL_TRUE;
   self->cond.top->else_allowed = GL_FALSE;
   self->cond.top->endif_required = GL_FALSE;
}

static GLvoid
pp_state_free (pp_state *self)
{
   pp_symbols_free (&self->symbols);
}

#define IS_FIRST_ID_CHAR(x) (((x) >= 'a' && (x) <= 'z') || ((x) >= 'A' && (x) <= 'Z') || (x) == '_')
#define IS_NEXT_ID_CHAR(x) (IS_FIRST_ID_CHAR(x) || ((x) >= '0' && (x) <= '9'))
#define IS_WHITE(x) ((x) == ' ' || (x) == '\n')
#define IS_NULL(x) ((x) == '\0')

#define SKIP_WHITE(x) do { while (IS_WHITE(*(x))) (x)++; } while (GL_FALSE)

typedef struct
{
   slang_string *output;
   const char *input;
   pp_state *state;
} expand_state;

static GLboolean
expand_defined (expand_state *e, slang_string *buffer)
{
   GLboolean in_paren = GL_FALSE;
   const char *id;

   /* Parse the optional opening parenthesis. */
   SKIP_WHITE(e->input);
   if (*e->input == '(') {
      e->input++;
      in_paren = GL_TRUE;
      SKIP_WHITE(e->input);
   }

   /* Parse operand. */
   if (!IS_FIRST_ID_CHAR(*e->input)) {
      slang_info_log_error (e->state->elog,
                            "preprocess error: identifier expected after operator 'defined'.");
      return GL_FALSE;
   }
   slang_string_reset (buffer);
   slang_string_pushc (buffer, *e->input++);
   while (IS_NEXT_ID_CHAR(*e->input))
      slang_string_pushc (buffer, *e->input++);
   id = slang_string_cstr (buffer);

   /* Check if the operand is defined. Output 1 if it is defined, output 0 if not. */
   if (pp_symbols_find (&e->state->symbols, id) == NULL)
      slang_string_pushs (e->output, " 0 ", 3);
   else
      slang_string_pushs (e->output, " 1 ", 3);

   /* Parse the closing parentehesis if the opening one was there. */
   if (in_paren) {
      SKIP_WHITE(e->input);
      if (*e->input != ')') {
         slang_info_log_error (e->state->elog, "preprocess error: ')' expected.");
         return GL_FALSE;
      }
      e->input++;
      SKIP_WHITE(e->input);
   }
   return GL_TRUE;
}

static GLboolean
expand (expand_state *, pp_symbols *);

static GLboolean
expand_symbol (expand_state *e, pp_symbol *symbol)
{
   expand_state es;

   /* If the macro has some parameters, we need to parse them. */
   if (symbol->parameters.count != 0) {
      GLuint i;

      /* Parse the opening parenthesis. */
      SKIP_WHITE(e->input);
      if (*e->input != '(') {
         slang_info_log_error (e->state->elog, "preprocess error: '(' expected.");
         return GL_FALSE;
      }
      e->input++;
      SKIP_WHITE(e->input);

      /* Parse macro actual parameters. This can be anything, separated by a colon.
       * TODO: What about nested/grouped parameters by parenthesis? */
      for (i = 0; i < symbol->parameters.count; i++) {
         if (*e->input == ')') {
            slang_info_log_error (e->state->elog, "preprocess error: unexpected ')'.");
            return GL_FALSE;
         }

         /* Eat all characters up to the comma or closing parentheses. */
         pp_symbol_reset (&symbol->parameters.symbols[i]);
         while (!IS_NULL(*e->input) && *e->input != ',' && *e->input != ')')
            slang_string_pushc (&symbol->parameters.symbols[i].replacement, *e->input++);

         /* If it was not the last paremeter, skip the comma. Otherwise, skip the
          * closing parentheses. */
         if (i + 1 == symbol->parameters.count) {
            /* This is the last paremeter - skip the closing parentheses. */
            if (*e->input != ')') {
               slang_info_log_error (e->state->elog, "preprocess error: ')' expected.");
               return GL_FALSE;
            }
            e->input++;
            SKIP_WHITE(e->input);
         }
         else {
            /* Skip the separating comma. */
            if (*e->input != ',') {
               slang_info_log_error (e->state->elog, "preprocess error: ',' expected.");
               return GL_FALSE;
            }
            e->input++;
            SKIP_WHITE(e->input);
         }
      }
   }

   /* Expand the macro. Use its parameters as a priority symbol list to expand
    * macro parameters correctly. */
   es.output = e->output;
   es.input = slang_string_cstr (&symbol->replacement);
   es.state = e->state;
   slang_string_pushc (e->output, ' ');
   if (!expand (&es, &symbol->parameters))
      return GL_FALSE;
   slang_string_pushc (e->output, ' ');
   return GL_TRUE;
}

/*
 * Function expand() expands source text from <input> to <output>. The expansion is made using
 * the list passed in <symbols> parameter. It allows us to expand macro formal parameters with
 * actual parameters. The global list of symbols from pp state is used when doing a recursive
 * call of expand().
 */

static GLboolean
expand (expand_state *e, pp_symbols *symbols)
{
   while (!IS_NULL(*e->input)) {
      if (IS_FIRST_ID_CHAR(*e->input)) {
         slang_string buffer;
         const char *id;

         /* Parse the identifier. */
         slang_string_init (&buffer);
         slang_string_pushc (&buffer, *e->input++);
         while (IS_NEXT_ID_CHAR(*e->input))
            slang_string_pushc (&buffer, *e->input++);
         id = slang_string_cstr (&buffer);

         /* Now check if the identifier is special in some way. The "defined" identifier is
          * actually an operator that we must handle here and expand it either to " 0 " or " 1 ".
          * The other identifiers start with "__" and we expand it to appropriate values
          * taken from the preprocessor state. */
         if (_mesa_strcmp (id, "defined") == 0) {
            if (!expand_defined (e, &buffer))
               return GL_FALSE;
         }
         else if (_mesa_strcmp (id, "__LINE__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->line);
            slang_string_pushc (e->output, ' ');
         }
         else if (_mesa_strcmp (id, "__FILE__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->file);
            slang_string_pushc (e->output, ' ');
         }
         else if (_mesa_strcmp (id, "__VERSION__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->version);
            slang_string_pushc (e->output, ' ');
         }
#if FEATURE_es2_glsl
         else if (_mesa_strcmp (id, "GL_ES") == 0 ||
                  _mesa_strcmp (id, "GL_FRAGMENT_PRECISION_HIGH") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, '1');
            slang_string_pushc (e->output, ' ');
         }
#endif
         else {
            pp_symbol *symbol;

            /* The list of symbols from <symbols> take precedence over the list from <state>.
             * Note that in some cases this is the same list so avoid double look-up. */
            symbol = pp_symbols_find (symbols, id);
            if (symbol == NULL && symbols != &e->state->symbols)
               symbol = pp_symbols_find (&e->state->symbols, id);

            /* If the symbol was found, recursively expand its definition. */
            if (symbol != NULL) {
               if (!expand_symbol (e, symbol)) {
                  slang_string_free (&buffer);
                  return GL_FALSE;
               }
            }
            else {
               slang_string_push (e->output, &buffer);
            }
         }
         slang_string_free (&buffer);
      }
      else if (IS_WHITE(*e->input)) {
         slang_string_pushc (e->output, *e->input++);
      }
      else {
         while (!IS_WHITE(*e->input) && !IS_NULL(*e->input) && !IS_FIRST_ID_CHAR(*e->input))
            slang_string_pushc (e->output, *e->input++);
      }
   }
   return GL_TRUE;
}

static GLboolean
parse_if (slang_string *output, const byte *prod, GLuint *pi, GLint *result, pp_state *state,
          grammar eid)
{
   const char *text;
   GLuint len;

   text = (const char *) (&prod[*pi]);
   len = _mesa_strlen (text);

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

      /* Expand the expression. */
      slang_string_init (&expr);
      es.output = &expr;
      es.input = text;
      es.state = state;
      if (!expand (&es, &state->symbols))
         return GL_FALSE;

      /* Execute the expression. */
      count = execute_expressions (output, eid, (const byte *) (slang_string_cstr (&expr)),
                                   results, state->elog);
      slang_string_free (&expr);
      if (count != 1)
         return GL_FALSE;