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xparser.c
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xparser.c
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#include "xparser.h"
#include <string.h>
#include "xlex.h"
#include "xlimits.h"
#include "xobject.h"
#include "xmem.h"
#define changebase(ls, b) (b?(ls)->curbase=(b):0)
static void statement(lexState* ls);
static void check(lexState* ls, int c) {
error_check(ls->t.token == c, "Expecting \"%c\"", c);
}
static void check_next(lexState* ls, int c) {
parser_next(ls);
check(ls, c);
}
static void checkAddItem(lexState* ls, XJson* item) {
if (!ls->json) {
error_check(item->t == XPRO_TARRAY || item->t == XPRO_TOBJECT, "JSON payload should be an object or array.");
ls->json = ls->curbase = item;
}
else addItem(ls->curbase, item);
}
static void statnull(lexState* ls) {
XJson* value = create_null();
checkAddItem(ls, value);
parser_next(ls);
}
static void statboolean(lexState* ls) {
XJson* value = create_bool(strcmp(ls->t.sem.s.str, "true") == 0);
checkAddItem(ls, value);
parser_next(ls);
}
static void statstring(lexState* ls) {
XJson* value = create_string(ls->t.sem.s.str);
checkAddItem(ls, value);
parser_next(ls);
}
static void statdouble(lexState* ls) {
XJson* value = create_double(ls->t.sem.n);
checkAddItem(ls, value);
parser_next(ls);
}
static void statinteger(lexState* ls) {
XJson* value = create_integer(ls->t.sem.i);
checkAddItem(ls, value);
parser_next(ls);
}
static void statarray(lexState* ls) {
XJson* parent = ls->curbase;
XJson* value = create_array();
checkAddItem(ls, value);
changebase(ls, value);
do {
parser_next(ls);
if (ls->t.token == LEX_EOF)
error_msg("Expecting 'string', 'number', 'null', 'true', 'false', '{', '['");
if (ls->t.token == ']') {
error_check(value->nchild == 0, "Expecting 'string', 'number', 'null', 'true', 'false', '{', '[' after ','");
break; /* empty array */
}
statement(ls);
} while (ls->t.token == ',');
changebase(ls, parent);
check(ls, ']');
parser_next(ls);
}
static void statobject(lexState* ls) {
XJson* parent = ls->curbase;
XJson* value = create_object();
checkAddItem(ls, value);
changebase(ls, value);
do {
parser_next(ls);
if (ls->t.token == LEX_EOF)
error_msg("Expecting 'string' after ','");
if (ls->t.token == '}') {
error_check(value->nchild == 0, "Expecting 'string' after ','");
break; /* empty object */
}
if (ls->t.token != LEX_STRING) error_msg("keys must be string."); /* key can only be 'string' */
size_t len = strlen(ls->t.sem.s.str) + 1;
char* key = realloc_(char, NULL, len); /* save key */
memcpy(key, ls->t.sem.s.str, len);
check_next(ls, ':');
parser_next(ls); /* skip ':' */
statement(ls);
ls->curbase->top->key = key; /* set last child's key */
} while (ls->t.token == ',');
changebase(ls, parent);
check(ls, '}');
parser_next(ls);
}
static void statement(lexState* ls) {
switch (ls->t.token) {
case '[': statarray(ls); break;
case '{': statobject(ls); break;
case LEX_NULL: statnull(ls); break;
case LEX_TRUE: case LEX_FALSE: statboolean(ls); break;
case LEX_STRING: statstring(ls); break;
case LEX_DOUBLE: statdouble(ls); break;
case LEX_INTEGER: statinteger(ls); break;
default: error_check(0, "Unexpected expression \"%s\"", ls->t.sem.s.str);
}
}
XJson* main_parser(const char* jsonstr) {
lexState ls;
xLex_init(&ls, jsonstr);
ls.current = getc(&ls);
parser_next(&ls);
statement(&ls);
error_check(ls.t.token == LEX_EOF, "Expecting 'EOF'");
XJson* json = ls.json;
xLex_free(&ls);
return json;
}