src/compiler/glsl/s_expression.cpp

   1 /* -*- c++ -*- */
   2 /*
   3  * Copyright © 2010 Intel Corporation
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22  * DEALINGS IN THE SOFTWARE.
  23  */
  24
  25 #include <assert.h>
  26 #include <stdio.h>
  27 #include <math.h>
  28 #include "s_expression.h"
  29
  30 s_symbol::s_symbol(const char *str, size_t n)
  31 {
  32    /* Assume the given string is already nul-terminated and in memory that
  33     * will live as long as this node.
  34     */
  35    assert(str[n] == '\0');
  36    this->str = str;
  37 }
  38
  39 s_list::s_list()
  40 {
  41 }
  42
  43 static void
  44 skip_whitespace(const char *&src, char *&symbol_buffer)
  45 {
  46    size_t n = strspn(src, " \v\t\r\n");
  47    src += n;
  48    symbol_buffer += n;
  49    /* Also skip Scheme-style comments: semi-colon 'til end of line */
  50    if (src[0] == ';') {
  51       n = strcspn(src, "\n");
  52       src += n;
  53       symbol_buffer += n;
  54       skip_whitespace(src, symbol_buffer);
  55    }
  56 }
  57
  58 static s_expression *
  59 read_atom(void *ctx, const char *&src, char *&symbol_buffer)
  60 {
  61    s_expression *expr = NULL;
  62
  63    skip_whitespace(src, symbol_buffer);
  64
  65    size_t n = strcspn(src, "( \v\t\r\n);");
  66    if (n == 0)
  67       return NULL; // no atom
  68
  69    // Check for the special symbol '+INF', which means +Infinity.  Note: C99
  70    // requires strtof to parse '+INF' as +Infinity, but we still support some
  71    // non-C99-compliant compilers (e.g. MSVC).
  72    if (n == 4 && strncmp(src, "+INF", 4) == 0) {
  73       expr = new(ctx) s_float(INFINITY);
  74    } else {
  75       // Check if the atom is a number.
  76       char *float_end = NULL;
  77       float f = _mesa_strtof(src, &float_end);
  78       if (float_end != src) {
  79          char *int_end = NULL;
  80          int i = strtol(src, &int_end, 10);
  81          // If strtof matched more characters, it must have a decimal part
  82          if (float_end > int_end)
  83             expr = new(ctx) s_float(f);
  84          else
  85             expr = new(ctx) s_int(i);
  86       } else {
  87          // Not a number; return a symbol.
  88          symbol_buffer[n] = '\0';
  89          expr = new(ctx) s_symbol(symbol_buffer, n);
  90       }
  91    }
  92
  93    src += n;
  94    symbol_buffer += n;
  95
  96    return expr;
  97 }
  98
  99 static s_expression *
 100 __read_expression(void *ctx, const char *&src, char *&symbol_buffer)
 101 {
 102    s_expression *atom = read_atom(ctx, src, symbol_buffer);
 103    if (atom != NULL)
 104       return atom;
 105
 106    skip_whitespace(src, symbol_buffer);
 107    if (src[0] == '(') {
 108       ++src;
 109       ++symbol_buffer;
 110
 111       s_list *list = new(ctx) s_list;
 112       s_expression *expr;
 113
 114       while ((expr = __read_expression(ctx, src, symbol_buffer)) != NULL) {
 115          list->subexpressions.push_tail(expr);
 116       }
 117       skip_whitespace(src, symbol_buffer);
 118       if (src[0] != ')') {
 119          printf("Unclosed expression (check your parenthesis).\n");
 120          return NULL;
 121       }
 122       ++src;
 123       ++symbol_buffer;
 124       return list;
 125    }
 126    return NULL;
 127 }
 128
 129 s_expression *
 130 s_expression::read_expression(void *ctx, const char *&src)
 131 {
 132    assert(src != NULL);
 133
 134    /* When we encounter a Symbol, we need to save a nul-terminated copy of
 135     * the string.  However, ralloc_strndup'ing every individual Symbol is
 136     * extremely expensive.  We could avoid this by simply overwriting the
 137     * next character (guaranteed to be whitespace, parens, or semicolon) with
 138     * a nul-byte.  But overwriting non-whitespace would mess up parsing.
 139     *
 140     * So, just copy the whole buffer ahead of time.  Walk both, leaving the
 141     * original source string unmodified, and altering the copy to contain the
 142     * necessary nul-bytes whenever we encounter a symbol.
 143     */
 144    char *symbol_buffer = ralloc_strdup(ctx, src);
 145    return __read_expression(ctx, src, symbol_buffer);
 146 }
 147
 148 void s_int::print()
 149 {
 150    printf("%d", this->val);
 151 }
 152
 153 void s_float::print()
 154 {
 155    printf("%f", this->val);
 156 }
 157
 158 void s_symbol::print()
 159 {
 160    printf("%s", this->str);
 161 }
 162
 163 void s_list::print()
 164 {
 165    printf("(");
 166    foreach_in_list(s_expression, expr, &this->subexpressions) {
 167       expr->print();
 168       if (!expr->next->is_tail_sentinel())
 169          printf(" ");
 170    }
 171    printf(")");
 172 }
 173
 174 // --------------------------------------------------
 175
 176 bool
 177 s_pattern::match(s_expression *expr)
 178 {
 179    switch (type)
 180    {
 181    case EXPR:   *p_expr = expr; break;
 182    case LIST:   if (expr->is_list())   *p_list   = (s_list *)   expr; break;
 183    case SYMBOL: if (expr->is_symbol()) *p_symbol = (s_symbol *) expr; break;
 184    case NUMBER: if (expr->is_number()) *p_number = (s_number *) expr; break;
 185    case INT:    if (expr->is_int())    *p_int    = (s_int *)    expr; break;
 186    case STRING:
 187       s_symbol *sym = SX_AS_SYMBOL(expr);
 188       if (sym != NULL && strcmp(sym->value(), literal) == 0)
 189          return true;
 190       return false;
 191    };
 192
 193    return *p_expr == expr;
 194 }
 195
 196 bool
 197 s_match(s_expression *top, unsigned n, s_pattern *pattern, bool partial)
 198 {
 199    s_list *list = SX_AS_LIST(top);
 200    if (list == NULL)
 201       return false;
 202
 203    unsigned i = 0;
 204    foreach_in_list(s_expression, expr, &list->subexpressions) {
 205       if (i >= n)
 206          return partial; /* More actual items than the pattern expected */
 207
 208       if (expr == NULL || !pattern[i].match(expr))
 209          return false;
 210
 211       i++;
 212    }
 213
 214    if (i < n)
 215       return false; /* Less actual items than the pattern expected */
 216
 217    return true;
 218 }