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* Copyright © 2010 Intel Corporation
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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#include "s_expression.h"
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s_symbol::s_symbol(const char *str, size_t n)
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/* Assume the given string is already nul-terminated and in memory that
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* will live as long as this node.
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assert(str[n] == '\0');
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skip_whitespace(const char *&src, char *&symbol_buffer)
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size_t n = strspn(src, " \v\t\r\n");
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/* Also skip Scheme-style comments: semi-colon 'til end of line */
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n = strcspn(src, "\n");
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skip_whitespace(src, symbol_buffer);
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read_atom(void *ctx, const char *&src, char *&symbol_buffer)
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s_expression *expr = NULL;
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skip_whitespace(src, symbol_buffer);
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size_t n = strcspn(src, "( \v\t\r\n);");
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return NULL; // no atom
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// Check for the special symbol '+INF', which means +Infinity. Note: C99
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// requires strtof to parse '+INF' as +Infinity, but we still support some
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// non-C99-compliant compilers (e.g. MSVC).
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if (n == 4 && strncmp(src, "+INF", 4) == 0) {
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expr = new(ctx) s_float(INFINITY);
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// Check if the atom is a number.
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char *float_end = NULL;
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float f = _mesa_strtof(src, &float_end);
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if (float_end != src) {
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int i = strtol(src, &int_end, 10);
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// If strtof matched more characters, it must have a decimal part
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if (float_end > int_end)
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expr = new(ctx) s_float(f);
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expr = new(ctx) s_int(i);
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// Not a number; return a symbol.
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symbol_buffer[n] = '\0';
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expr = new(ctx) s_symbol(symbol_buffer, n);
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static s_expression *
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__read_expression(void *ctx, const char *&src, char *&symbol_buffer)
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s_expression *atom = read_atom(ctx, src, symbol_buffer);
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skip_whitespace(src, symbol_buffer);
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s_list *list = new(ctx) s_list;
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while ((expr = __read_expression(ctx, src, symbol_buffer)) != NULL) {
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list->subexpressions.push_tail(expr);
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skip_whitespace(src, symbol_buffer);
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printf("Unclosed expression (check your parenthesis).\n");
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s_expression::read_expression(void *ctx, const char *&src)
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/* When we encounter a Symbol, we need to save a nul-terminated copy of
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* the string. However, ralloc_strndup'ing every individual Symbol is
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* extremely expensive. We could avoid this by simply overwriting the
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* next character (guaranteed to be whitespace, parens, or semicolon) with
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* a nul-byte. But overwriting non-whitespace would mess up parsing.
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* So, just copy the whole buffer ahead of time. Walk both, leaving the
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* original source string unmodified, and altering the copy to contain the
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* necessary nul-bytes whenever we encounter a symbol.
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char *symbol_buffer = ralloc_strdup(ctx, src);
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return __read_expression(ctx, src, symbol_buffer);
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printf("%d", this->val);
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void s_float::print()
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printf("%f", this->val);
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void s_symbol::print()
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printf("%s", this->str);
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foreach_in_list(s_expression, expr, &this->subexpressions) {
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if (!expr->next->is_tail_sentinel())
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// --------------------------------------------------
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s_pattern::match(s_expression *expr)
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case EXPR: *p_expr = expr; break;
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case LIST: if (expr->is_list()) *p_list = (s_list *) expr; break;
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case SYMBOL: if (expr->is_symbol()) *p_symbol = (s_symbol *) expr; break;
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case NUMBER: if (expr->is_number()) *p_number = (s_number *) expr; break;
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case INT: if (expr->is_int()) *p_int = (s_int *) expr; break;
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s_symbol *sym = SX_AS_SYMBOL(expr);
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if (sym != NULL && strcmp(sym->value(), literal) == 0)
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return *p_expr == expr;
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s_match(s_expression *top, unsigned n, s_pattern *pattern, bool partial)
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s_list *list = SX_AS_LIST(top);
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foreach_in_list(s_expression, expr, &list->subexpressions) {
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return partial; /* More actual items than the pattern expected */
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if (expr == NULL || !pattern[i].match(expr))
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return false; /* Less actual items than the pattern expected */