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      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 <limits>
     27 #include "s_expression.h"
     28 
     29 s_symbol::s_symbol(const char *str, size_t n)
     30 {
     31    /* Assume the given string is already nul-terminated and in memory that
     32     * will live as long as this node.
     33     */
     34    assert(str[n] == '\0');
     35    this->str = str;
     36 }
     37 
     38 s_list::s_list()
     39 {
     40 }
     41 
     42 static void
     43 skip_whitespace(const char *&src, char *&symbol_buffer)
     44 {
     45    size_t n = strspn(src, " \v\t\r\n");
     46    src += n;
     47    symbol_buffer += n;
     48    /* Also skip Scheme-style comments: semi-colon 'til end of line */
     49    if (src[0] == ';') {
     50       n = strcspn(src, "\n");
     51       src += n;
     52       symbol_buffer += n;
     53       skip_whitespace(src, symbol_buffer);
     54    }
     55 }
     56 
     57 static s_expression *
     58 read_atom(void *ctx, const char *&src, char *&symbol_buffer)
     59 {
     60    s_expression *expr = NULL;
     61 
     62    skip_whitespace(src, symbol_buffer);
     63 
     64    size_t n = strcspn(src, "( \v\t\r\n);");
     65    if (n == 0)
     66       return NULL; // no atom
     67 
     68    // Check for the special symbol '+INF', which means +Infinity.  Note: C99
     69    // requires strtod to parse '+INF' as +Infinity, but we still support some
     70    // non-C99-compliant compilers (e.g. MSVC).
     71    if (n == 4 && strncmp(src, "+INF", 4) == 0) {
     72       expr = new(ctx) s_float(std::numeric_limits<float>::infinity());
     73    } else {
     74       // Check if the atom is a number.
     75       char *float_end = NULL;
     76       double f = glsl_strtod(src, &float_end);
     77       if (float_end != src) {
     78          char *int_end = NULL;
     79          int i = strtol(src, &int_end, 10);
     80          // If strtod matched more characters, it must have a decimal part
     81          if (float_end > int_end)
     82             expr = new(ctx) s_float(f);
     83          else
     84             expr = new(ctx) s_int(i);
     85       } else {
     86          // Not a number; return a symbol.
     87          symbol_buffer[n] = '\0';
     88          expr = new(ctx) s_symbol(symbol_buffer, n);
     89       }
     90    }
     91 
     92    src += n;
     93    symbol_buffer += n;
     94 
     95    return expr;
     96 }
     97 
     98 static s_expression *
     99 __read_expression(void *ctx, const char *&src, char *&symbol_buffer)
    100 {
    101    s_expression *atom = read_atom(ctx, src, symbol_buffer);
    102    if (atom != NULL)
    103       return atom;
    104 
    105    skip_whitespace(src, symbol_buffer);
    106    if (src[0] == '(') {
    107       ++src;
    108       ++symbol_buffer;
    109 
    110       s_list *list = new(ctx) s_list;
    111       s_expression *expr;
    112 
    113       while ((expr = __read_expression(ctx, src, symbol_buffer)) != NULL) {
    114 	 list->subexpressions.push_tail(expr);
    115       }
    116       skip_whitespace(src, symbol_buffer);
    117       if (src[0] != ')') {
    118 	 printf("Unclosed expression (check your parenthesis).\n");
    119 	 return NULL;
    120       }
    121       ++src;
    122       ++symbol_buffer;
    123       return list;
    124    }
    125    return NULL;
    126 }
    127 
    128 s_expression *
    129 s_expression::read_expression(void *ctx, const char *&src)
    130 {
    131    assert(src != NULL);
    132 
    133    /* When we encounter a Symbol, we need to save a nul-terminated copy of
    134     * the string.  However, ralloc_strndup'ing every individual Symbol is
    135     * extremely expensive.  We could avoid this by simply overwriting the
    136     * next character (guaranteed to be whitespace, parens, or semicolon) with
    137     * a nul-byte.  But overwriting non-whitespace would mess up parsing.
    138     *
    139     * So, just copy the whole buffer ahead of time.  Walk both, leaving the
    140     * original source string unmodified, and altering the copy to contain the
    141     * necessary nul-bytes whenever we encounter a symbol.
    142     */
    143    char *symbol_buffer = ralloc_strdup(ctx, src);
    144    return __read_expression(ctx, src, symbol_buffer);
    145 }
    146 
    147 void s_int::print()
    148 {
    149    printf("%d", this->val);
    150 }
    151 
    152 void s_float::print()
    153 {
    154    printf("%f", this->val);
    155 }
    156 
    157 void s_symbol::print()
    158 {
    159    printf("%s", this->str);
    160 }
    161 
    162 void s_list::print()
    163 {
    164    printf("(");
    165    foreach_iter(exec_list_iterator, it, this->subexpressions) {
    166       s_expression *expr = (s_expression*) it.get();
    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_iter(exec_list_iterator, it, list->subexpressions) {
    205       if (i >= n)
    206 	 return partial; /* More actual items than the pattern expected */
    207 
    208       s_expression *expr = (s_expression *) it.get();
    209       if (expr == NULL || !pattern[i].match(expr))
    210 	 return false;
    211 
    212       i++;
    213    }
    214 
    215    if (i < n)
    216       return false; /* Less actual items than the pattern expected */
    217 
    218    return true;
    219 }
    220