303 lines
7.5 KiB
C
303 lines
7.5 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include "parser.h"
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static struct token *get_token(struct parser *parser) {
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return lex_token(&parser->lexer);
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}
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static int token_is(struct parser *parser, enum token_type type) {
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return get_token(parser)->type == type;
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}
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static double token_num(struct parser *parser) {
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return get_token(parser)->val.num;
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}
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static enum math_fn token_fn(struct parser *parser) {
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return get_token(parser)->val.fn;
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}
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static void next_token(struct parser *parser) {
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lex_next(&parser->lexer);
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}
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static int accept_token(struct parser *parser, enum token_type type) {
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if (token_is(parser, type)) {
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next_token(parser);
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return 1;
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}
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return 0;
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}
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static void error_bad_alloc(struct parser *parser) {
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error_set(&parser->eb, ERR_BAD_ALLOC);
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error_printf(&parser->eb, "Out of memory\n");
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}
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static void error_expected_one_of(struct parser *parser, const int expected[]) {
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static const char* token_name[] = {
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"end of expression",
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"lexer error",
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"constant",
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"+",
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"-",
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"*",
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"/",
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"^",
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"x",
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"function name",
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"(",
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")"
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};
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size_t i;
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enum token_type got = get_token(parser)->type;
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if (got == TOK_ERROR) {
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error_set(&parser->eb, lex_get_error(&parser->lexer));
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error_printf(&parser->eb, "Lexer error - %s", lex_get_error_text(&parser->lexer));
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return;
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}
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error_set(&parser->eb, ERR_INVALID_FUNCTION);
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error_printf(&parser->eb, "Syntax error - expected ");
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for (i = 0; expected[i] >= 0; ++i) {
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if (i > 0)
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error_printf(&parser->eb, ", ");
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error_printf(&parser->eb, "'%s'", token_name[expected[i]]);
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}
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error_printf(&parser->eb, " - but got '%s'\n", token_name[got]);
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lex_print_position(&parser->lexer, &parser->eb);
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}
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static void error_expected_single(struct parser *parser, enum token_type expected) {
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static int expected_arr[] = { -1, -1 };
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expected_arr[0] = expected;
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error_expected_one_of(parser, expected_arr);
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}
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static struct expr_node* parse_subexpression(struct parser *parser);
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static struct expr_node* parse_bracketed(struct parser *parser) {
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struct expr_node* node;
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if (!accept_token(parser, TOK_LEFT_PAREN)) {
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error_expected_single(parser, TOK_LEFT_PAREN);
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return NULL;
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}
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if (!(node = parse_subexpression(parser)))
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return NULL;
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if (!accept_token(parser, TOK_RIGHT_PAREN)) {
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error_expected_single(parser, TOK_RIGHT_PAREN);
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node_free(node);
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return NULL;
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}
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return node;
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}
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static struct expr_node *parse_base(struct parser *parser) {
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struct expr_node *node, *inner;
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if (token_is(parser, TOK_NUMBER)) {
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double val = token_num(parser);
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next_token(parser);
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if (!(node = node_create_const(val))) {
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error_bad_alloc(parser);
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return NULL;
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}
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return node;
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}
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if (accept_token(parser, TOK_X)) {
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if (!(node = node_create_x())) {
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error_bad_alloc(parser);
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return NULL;
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}
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return node;
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}
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if (token_is(parser, TOK_FUNCTION)) {
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enum math_fn fn = token_fn(parser);
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next_token(parser);
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if (!(inner = parse_bracketed(parser)))
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return NULL;
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if (!(node = node_create_fn(fn, inner))) {
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node_free(inner);
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error_bad_alloc(parser);
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return NULL;
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}
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return node;
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}
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if (token_is(parser, TOK_LEFT_PAREN)) {
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return parse_bracketed(parser);
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}
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{
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static const int expected[] = { TOK_NUMBER, TOK_X, TOK_FUNCTION, TOK_LEFT_PAREN, -1 };
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error_expected_one_of(parser, expected);
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}
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return NULL;
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}
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static struct expr_node *parse_unary(struct parser *parser);
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static struct expr_node *parse_factor(struct parser *parser) {
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struct expr_node* node, * new_node, * inner;
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if (!(node = parse_base(parser)))
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return NULL;
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if (accept_token(parser, TOK_POWER)) {
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if (!(inner = parse_unary(parser))) {
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node_free(node);
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return NULL;
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}
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if (!(new_node = node_create_pow(node, inner))) {
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error_bad_alloc(parser);
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node_free(node);
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node_free(inner);
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return NULL;
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}
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return new_node;
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}
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return node;
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}
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static struct expr_node* parse_unary(struct parser *parser) {
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if (accept_token(parser, TOK_MINUS)) {
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struct expr_node *node, *inner;
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if (!(inner = parse_factor(parser)))
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return NULL;
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if (!(node = node_create_neg(inner))) {
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error_bad_alloc(parser);
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node_free(inner);
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return NULL;
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}
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return node;
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}
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accept_token(parser, TOK_PLUS);
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return parse_factor(parser);
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}
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static struct expr_node *parse_term(struct parser *parser) {
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struct expr_node *node, *new_node, *inner;
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if (!(node = parse_unary(parser)))
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return NULL;
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while (1) {
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struct expr_node *(*create_node)(struct expr_node *left, struct expr_node *right);
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if (accept_token(parser, TOK_MULTIPLY))
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create_node = node_create_mult;
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else if (accept_token(parser, TOK_DIVIDE))
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create_node = node_create_div;
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else
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break;
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if (!(inner = parse_unary(parser))) {
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node_free(node);
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return NULL;
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}
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if (!(new_node = create_node(node, inner))) {
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error_bad_alloc(parser);
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node_free(node);
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node_free(inner);
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return NULL;
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}
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node = new_node;
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}
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return node;
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}
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static struct expr_node *parse_subexpression(struct parser *parser) {
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struct expr_node *node, *new_node, *inner;
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if (!(node = parse_term(parser)))
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return NULL;
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while (1) {
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struct expr_node *(*create_node)(struct expr_node *left, struct expr_node *right);
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if (accept_token(parser, TOK_PLUS))
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create_node = node_create_add;
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else if (accept_token(parser, TOK_MINUS))
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create_node = node_create_sub;
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else
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break;
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if (!(inner = parse_term(parser))) {
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node_free(node);
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return NULL;
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}
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if (!(new_node = create_node(node, inner))) {
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error_bad_alloc(parser);
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node_free(node);
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node_free(inner);
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return NULL;
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}
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node = new_node;
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}
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return node;
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}
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static struct expr_node *parse_expression(struct parser *parser) {
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struct expr_node *node;
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if (!(node = parse_subexpression(parser)))
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return NULL;
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if (!token_is(parser, TOK_EOF)) {
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error_expected_single(parser, TOK_EOF);
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node_free(node);
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return NULL;
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}
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return node;
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}
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void parser_init(struct parser *parser) {
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error_buffer_init(&parser->eb);
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}
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struct expr_node *parser_parse(struct parser *parser, const char *str) {
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lex_init(&parser->lexer, str);
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return parse_expression(parser);
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}
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enum error_code parser_get_error(const struct parser *parser) {
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return error_get(&parser->eb);
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}
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const char *parser_get_error_text(const struct parser *parser) {
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return error_get_text(&parser->eb);
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} |