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stedolan-jq/c/jv_parse.c

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2012-09-01 19:16:43 +01:00
#include <stdio.h>
#include <stdlib.h>
#include "jv.h"
#include "jv_dtoa.h"
jv stack[1000];
int stackpos = 0;
jv next;
int hasnext;
typedef const char* presult;
#define TRY(x) do {presult msg__ = (x); if (msg__) return msg__; } while(0)
#ifdef __GNUC__
#define pfunc __attribute__((warn_unused_result)) presult
#else
#define pfunc presult
#endif
pfunc value(jv val) {
if (hasnext) return "Expected separator between values";
hasnext = 1;
next = val;
return 0;
}
void push(jv v) {
stack[stackpos++] = v;
}
pfunc token(char ch) {
switch (ch) {
case '[':
if (hasnext) return "Expected separator between values";
push(jv_array());
break;
case '{':
if (hasnext) return "Expected separator between values";
push(jv_object());
break;
case ':':
if (!hasnext)
return "Expected string key before ':'";
if (stackpos == 0 || jv_get_kind(stack[stackpos-1]) != JV_KIND_OBJECT)
return "':' not as part of an object";
if (jv_get_kind(next) != JV_KIND_STRING)
return "Object keys must be strings";
push(next);
hasnext = 0;
break;
case ',':
if (!hasnext)
return "Expected value before ','";
if (stackpos == 0)
return "',' not as part of an object or array";
if (jv_get_kind(stack[stackpos-1]) == JV_KIND_ARRAY) {
stack[stackpos-1] = jv_array_append(stack[stackpos-1], next);
hasnext = 0;
} else if (jv_get_kind(stack[stackpos-1]) == JV_KIND_STRING) {
assert(stackpos > 1 && jv_get_kind(stack[stackpos-2]) == JV_KIND_OBJECT);
stack[stackpos-2] = jv_object_set(stack[stackpos-2], stack[stackpos-1], next);
stackpos--;
hasnext = 0;
} else {
// this case hits on input like {"a", "b"}
return "Objects must consist of key:value pairs";
}
break;
case ']':
if (stackpos == 0 || jv_get_kind(stack[stackpos-1]) != JV_KIND_ARRAY)
return "Unmatched ']'";
if (hasnext) {
stack[stackpos-1] = jv_array_append(stack[stackpos-1], next);
hasnext = 0;
} else {
if (jv_array_length(jv_copy(stack[stackpos-1])) != 0) {
// this case hits on input like [1,2,3,]
return "Expected another array element";
}
}
hasnext = 1;
next = stack[--stackpos];
break;
case '}':
if (stackpos == 0)
return "Unmatched '}'";
if (hasnext) {
if (jv_get_kind(stack[stackpos-1]) != JV_KIND_STRING)
return "Objects must consist of key:value pairs";
assert(stackpos > 1 && jv_get_kind(stack[stackpos-2]) == JV_KIND_OBJECT);
stack[stackpos-2] = jv_object_set(stack[stackpos-2], stack[stackpos-1], next);
stackpos--;
hasnext = 0;
} else {
if (jv_get_kind(stack[stackpos-1]) != JV_KIND_OBJECT)
return "Unmatched '}'";
// FIXME: assert object empty
}
hasnext = 1;
next = stack[--stackpos];
break;
}
return 0;
}
char tokenbuf[1000];
int tokenpos;
struct dtoa_context dtoa;
void tokenadd(char c) {
tokenbuf[tokenpos++] = c;
}
int unhex4(char* hex) {
int r = 0;
for (int i=0; i<4; i++) {
char c = *hex++;
int n;
if ('0' <= c && c <= '9') n = c - '0';
else if ('a' <= c && c <= 'f') n = c - 'a' + 10;
else if ('A' <= c && c <= 'F') n = c - 'A' + 10;
r <<= 4;
r |= n;
}
return r;
}
int utf8_encode(int codepoint, char* out) {
assert(codepoint >= 0 && codepoint <= 0x10FFFF);
char* start = out;
if (codepoint <= 0x7F) {
*out++ = codepoint;
} else if (codepoint <= 0x7FF) {
*out++ = 0xC0 + ((codepoint & 0x7C0) >> 6);
*out++ = 0x80 + ((codepoint & 0x03F));
} else if(codepoint <= 0xFFFF) {
*out++ = 0xE0 + ((codepoint & 0xF000) >> 12);
*out++ = 0x80 + ((codepoint & 0x0FC0) >> 6);
*out++ = 0x80 + ((codepoint & 0x003F));
} else {
*out++ = 0xF0 + ((codepoint & 0x1C0000) >> 18);
*out++ = 0x80 + ((codepoint & 0x03F000) >> 12);
*out++ = 0x80 + ((codepoint & 0x000FC0) >> 6);
*out++ = 0x80 + ((codepoint & 0x00003F));
}
return out - start;
}
pfunc found_string() {
char* in = tokenbuf;
char* out = tokenbuf;
char* end = tokenbuf + tokenpos;
while (in < end) {
char c = *in++;
if (c == '\\') {
if (in >= end)
return "Expected escape character at end of string";
c = *in++;
switch (c) {
case '\\':
case '"':
case '/': *out++ = c; break;
case 'b': *out++ = '\b'; break;
case 'f': *out++ = '\f'; break;
case 't': *out++ = '\t'; break;
case 'n': *out++ = '\n'; break;
case 'r': *out++ = '\r'; break;
case 'u':
/* ahh, the complicated case */
if (in + 4 > end)
return "Invalid \\uXXXX escape";
unsigned long codepoint = unhex4(in);
in += 4;
if (0xD800 <= codepoint && codepoint <= 0xDBFF) {
/* who thought UTF-16 surrogate pairs were a good idea? */
if (in + 6 > end || in[0] != '\\' || in[1] != 'u')
return "Invalid \\uXXXX\\uXXXX surrogate pair escape";
unsigned long surrogate = unhex4(in+2);
if (!(0xDC00 <= surrogate && surrogate <= 0xDFFF))
return "Invalid \\uXXXX\\uXXXX surrogate pair escape";
in += 6;
codepoint = 0x10000 + (((codepoint - 0xD800) << 10)
|(surrogate - 0xDC00));
}
// FIXME assert valid codepoint
out += utf8_encode(codepoint, out);
break;
default:
return "Invalid escape";
}
} else {
*out++ = c;
}
}
TRY(value(jv_string_sized(tokenbuf, out - tokenbuf)));
tokenpos=0;
return 0;
}
pfunc check_literal() {
if (tokenpos == 0) return 0;
const char* pattern = 0;
int plen;
jv v;
switch (tokenbuf[0]) {
case 't': pattern = "true"; plen = 4; v = jv_true(); break;
case 'f': pattern = "false"; plen = 5; v = jv_false(); break;
case 'n': pattern = "null"; plen = 4; v = jv_null(); break;
}
if (pattern) {
if (tokenpos != plen) return "Invalid literal";
for (int i=0; i<plen; i++)
if (tokenbuf[i] != pattern[i])
return "Invalid literal";
TRY(value(v));
} else {
// FIXME: better parser
tokenbuf[tokenpos] = 0; // FIXME: invalid
char* end = 0;
double d = jvp_strtod(&dtoa, tokenbuf, &end);
if (end == 0 || *end != 0)
return "Invalid numeric literal";
TRY(value(jv_number(d)));
}
tokenpos=0;
return 0;
}
typedef enum {
LITERAL,
WHITESPACE,
STRUCTURE,
QUOTE,
INVALID
} chclass;
chclass classify(char c) {
switch (c) {
case ' ':
case '\t':
case '\r':
case '\n':
return WHITESPACE;
case '"':
return QUOTE;
case '[':
case ',':
case ']':
case '{':
case ':':
case '}':
return STRUCTURE;
default:
return LITERAL;
}
}
enum state {
NORMAL,
STRING,
STRING_ESCAPE
};
enum state st = NORMAL;
pfunc scan(char ch) {
if (st == NORMAL) {
chclass cls = classify(ch);
if (cls != LITERAL) {
TRY(check_literal());
}
switch (cls) {
case LITERAL:
tokenadd(ch);
break;
case WHITESPACE:
break;
case QUOTE:
st = STRING;
break;
case STRUCTURE:
TRY(token(ch));
break;
case INVALID:
return "Invalid character";
}
} else {
if (ch == '"' && st == STRING) {
TRY(found_string());
st = NORMAL;
} else {
tokenadd(ch);
if (ch == '\\' && st == STRING) {
st = STRING_ESCAPE;
} else {
st = STRING;
}
}
}
return 0;
}
pfunc finish() {
assert(st == NORMAL);
TRY(check_literal());
if (stackpos != 0)
return "Unfinished JSON term";
// this will happen on the empty string
if (!hasnext)
return "Expected JSON value";
return 0;
}
int main(int argc, char* argv[]) {
assert(argc == 2);
jvp_dtoa_context_init(&dtoa);
char* p = argv[1];
char ch;
while ((ch = *p++)) {
presult msg = scan(ch);
if (msg){
printf("ERROR: %s\n", msg);
return 1;
}
}
presult msg = finish();
if (msg) {
printf("ERROR: %s\n", msg);
return 1;
}
jvp_dtoa_context_free(&dtoa);
jv_dump(next);
printf("\n");
return 0;
}