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f7c052747e
qemu/json-lexer.c
Paolo Bonzini f7c052747e implement optional lookahead in json lexer 
Not requiring one extra character when lookahead is not necessary
ensures that clients behave properly even if they, for example,
send QMP requests without a trailing newline.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2010-06-11 15:25:14 -03:00

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/*
* JSON lexer
*
* Copyright IBM, Corp. 2009
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qstring.h"
#include "qlist.h"
#include "qdict.h"
#include "qint.h"
#include "qemu-common.h"
#include "json-lexer.h"
/*
* \"([^\\\"]|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*\"
* '([^\\']|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*'
* 0|([1-9][0-9]*(.[0-9]+)?([eE]([-+])?[0-9]+))
* [{}\[\],:]
* [a-z]+
*
*/
enum json_lexer_state {
ERROR = 0,
IN_DONE_STRING,
IN_DQ_UCODE3,
IN_DQ_UCODE2,
IN_DQ_UCODE1,
IN_DQ_UCODE0,
IN_DQ_STRING_ESCAPE,
IN_DQ_STRING,
IN_SQ_UCODE3,
IN_SQ_UCODE2,
IN_SQ_UCODE1,
IN_SQ_UCODE0,
IN_SQ_STRING_ESCAPE,
IN_SQ_STRING,
IN_ZERO,
IN_DIGITS,
IN_DIGIT,
IN_EXP_E,
IN_MANTISSA,
IN_MANTISSA_DIGITS,
IN_NONZERO_NUMBER,
IN_NEG_NONZERO_NUMBER,
IN_KEYWORD,
IN_ESCAPE,
IN_ESCAPE_L,
IN_ESCAPE_LL,
IN_ESCAPE_I,
IN_ESCAPE_I6,
IN_ESCAPE_I64,
IN_ESCAPE_DONE,
IN_WHITESPACE,
IN_OPERATOR_DONE,
IN_START,
};
#define TERMINAL(state) [0 ... 0x7F] = (state)
/* Return whether TERMINAL is a terminal state and the transition to it
from OLD_STATE required lookahead. This happens whenever the table
below uses the TERMINAL macro. */
#define TERMINAL_NEEDED_LOOKAHEAD(old_state, terminal) \
(json_lexer[(old_state)][0] == (terminal))
static const uint8_t json_lexer[][256] = {
[IN_DONE_STRING] = {
TERMINAL(JSON_STRING),
},
/* double quote string */
[IN_DQ_UCODE3] = {
['0' ... '9'] = IN_DQ_STRING,
['a' ... 'f'] = IN_DQ_STRING,
['A' ... 'F'] = IN_DQ_STRING,
},
[IN_DQ_UCODE2] = {
['0' ... '9'] = IN_DQ_UCODE3,
['a' ... 'f'] = IN_DQ_UCODE3,
['A' ... 'F'] = IN_DQ_UCODE3,
},
[IN_DQ_UCODE1] = {
['0' ... '9'] = IN_DQ_UCODE2,
['a' ... 'f'] = IN_DQ_UCODE2,
['A' ... 'F'] = IN_DQ_UCODE2,
},
[IN_DQ_UCODE0] = {
['0' ... '9'] = IN_DQ_UCODE1,
['a' ... 'f'] = IN_DQ_UCODE1,
['A' ... 'F'] = IN_DQ_UCODE1,
},
[IN_DQ_STRING_ESCAPE] = {
['b'] = IN_DQ_STRING,
['f'] = IN_DQ_STRING,
['n'] = IN_DQ_STRING,
['r'] = IN_DQ_STRING,
['t'] = IN_DQ_STRING,
['/'] = IN_DQ_STRING,
['\\'] = IN_DQ_STRING,
['\''] = IN_DQ_STRING,
['\"'] = IN_DQ_STRING,
['u'] = IN_DQ_UCODE0,
},
[IN_DQ_STRING] = {
[1 ... 0xFF] = IN_DQ_STRING,
['\\'] = IN_DQ_STRING_ESCAPE,
['"'] = IN_DONE_STRING,
},
/* single quote string */
[IN_SQ_UCODE3] = {
['0' ... '9'] = IN_SQ_STRING,
['a' ... 'f'] = IN_SQ_STRING,
['A' ... 'F'] = IN_SQ_STRING,
},
[IN_SQ_UCODE2] = {
['0' ... '9'] = IN_SQ_UCODE3,
['a' ... 'f'] = IN_SQ_UCODE3,
['A' ... 'F'] = IN_SQ_UCODE3,
},
[IN_SQ_UCODE1] = {
['0' ... '9'] = IN_SQ_UCODE2,
['a' ... 'f'] = IN_SQ_UCODE2,
['A' ... 'F'] = IN_SQ_UCODE2,
},
[IN_SQ_UCODE0] = {
['0' ... '9'] = IN_SQ_UCODE1,
['a' ... 'f'] = IN_SQ_UCODE1,
['A' ... 'F'] = IN_SQ_UCODE1,
},
[IN_SQ_STRING_ESCAPE] = {
['b'] = IN_SQ_STRING,
['f'] = IN_SQ_STRING,
['n'] = IN_SQ_STRING,
['r'] = IN_SQ_STRING,
['t'] = IN_SQ_STRING,
['/'] = IN_DQ_STRING,
['\\'] = IN_DQ_STRING,
['\''] = IN_SQ_STRING,
['\"'] = IN_SQ_STRING,
['u'] = IN_SQ_UCODE0,
},
[IN_SQ_STRING] = {
[1 ... 0xFF] = IN_SQ_STRING,
['\\'] = IN_SQ_STRING_ESCAPE,
['\''] = IN_DONE_STRING,
},
/* Zero */
[IN_ZERO] = {
TERMINAL(JSON_INTEGER),
['0' ... '9'] = ERROR,
['.'] = IN_MANTISSA,
},
/* Float */
[IN_DIGITS] = {
TERMINAL(JSON_FLOAT),
['0' ... '9'] = IN_DIGITS,
},
[IN_DIGIT] = {
['0' ... '9'] = IN_DIGITS,
},
[IN_EXP_E] = {
['-'] = IN_DIGIT,
['+'] = IN_DIGIT,
['0' ... '9'] = IN_DIGITS,
},
[IN_MANTISSA_DIGITS] = {
TERMINAL(JSON_FLOAT),
['0' ... '9'] = IN_MANTISSA_DIGITS,
['e'] = IN_EXP_E,
['E'] = IN_EXP_E,
},
[IN_MANTISSA] = {
['0' ... '9'] = IN_MANTISSA_DIGITS,
},
/* Number */
[IN_NONZERO_NUMBER] = {
TERMINAL(JSON_INTEGER),
['0' ... '9'] = IN_NONZERO_NUMBER,
['e'] = IN_EXP_E,
['E'] = IN_EXP_E,
['.'] = IN_MANTISSA,
},
[IN_NEG_NONZERO_NUMBER] = {
['0'] = IN_ZERO,
['1' ... '9'] = IN_NONZERO_NUMBER,
},
/* keywords */
[IN_KEYWORD] = {
TERMINAL(JSON_KEYWORD),
['a' ... 'z'] = IN_KEYWORD,
},
/* whitespace */
[IN_WHITESPACE] = {
TERMINAL(JSON_SKIP),
[' '] = IN_WHITESPACE,
['\t'] = IN_WHITESPACE,
['\r'] = IN_WHITESPACE,
['\n'] = IN_WHITESPACE,
},
/* operator */
[IN_OPERATOR_DONE] = {
TERMINAL(JSON_OPERATOR),
},
/* escape */
[IN_ESCAPE_DONE] = {
TERMINAL(JSON_ESCAPE),
},
[IN_ESCAPE_LL] = {
['d'] = IN_ESCAPE_DONE,
},
[IN_ESCAPE_L] = {
['d'] = IN_ESCAPE_DONE,
['l'] = IN_ESCAPE_LL,
},
[IN_ESCAPE_I64] = {
['d'] = IN_ESCAPE_DONE,
},
[IN_ESCAPE_I6] = {
['4'] = IN_ESCAPE_I64,
},
[IN_ESCAPE_I] = {
['6'] = IN_ESCAPE_I6,
},
[IN_ESCAPE] = {
['d'] = IN_ESCAPE_DONE,
['i'] = IN_ESCAPE_DONE,
['p'] = IN_ESCAPE_DONE,
['s'] = IN_ESCAPE_DONE,
['f'] = IN_ESCAPE_DONE,
['l'] = IN_ESCAPE_L,
['I'] = IN_ESCAPE_I,
},
/* top level rule */
[IN_START] = {
['"'] = IN_DQ_STRING,
['\''] = IN_SQ_STRING,
['0'] = IN_ZERO,
['1' ... '9'] = IN_NONZERO_NUMBER,
['-'] = IN_NEG_NONZERO_NUMBER,
['{'] = IN_OPERATOR_DONE,
['}'] = IN_OPERATOR_DONE,
['['] = IN_OPERATOR_DONE,
[']'] = IN_OPERATOR_DONE,
[','] = IN_OPERATOR_DONE,
[':'] = IN_OPERATOR_DONE,
['a' ... 'z'] = IN_KEYWORD,
['%'] = IN_ESCAPE,
[' '] = IN_WHITESPACE,
['\t'] = IN_WHITESPACE,
['\r'] = IN_WHITESPACE,
['\n'] = IN_WHITESPACE,
},
};
void json_lexer_init(JSONLexer *lexer, JSONLexerEmitter func)
{
lexer->emit = func;
lexer->state = IN_START;
lexer->token = qstring_new();
lexer->x = lexer->y = 0;
}
static int json_lexer_feed_char(JSONLexer *lexer, char ch)
{
int char_consumed, new_state;
lexer->x++;
if (ch == '\n') {
lexer->x = 0;
lexer->y++;
}
do {
new_state = json_lexer[lexer->state][(uint8_t)ch];
char_consumed = !TERMINAL_NEEDED_LOOKAHEAD(lexer->state, new_state);
if (char_consumed) {
qstring_append_chr(lexer->token, ch);
}
switch (new_state) {
case JSON_OPERATOR:
case JSON_ESCAPE:
case JSON_INTEGER:
case JSON_FLOAT:
case JSON_KEYWORD:
case JSON_STRING:
lexer->emit(lexer, lexer->token, new_state, lexer->x, lexer->y);
case JSON_SKIP:
QDECREF(lexer->token);
lexer->token = qstring_new();
new_state = IN_START;
break;
case ERROR:
return -EINVAL;
default:
break;
}
lexer->state = new_state;
} while (!char_consumed);
return 0;
}
int json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size)
{
size_t i;
for (i = 0; i < size; i++) {
int err;
err = json_lexer_feed_char(lexer, buffer[i]);
if (err < 0) {
return err;
}
}
return 0;
}
int json_lexer_flush(JSONLexer *lexer)
{
return lexer->state == IN_START ? 0 : json_lexer_feed_char(lexer, 0);
}
void json_lexer_destroy(JSONLexer *lexer)
{
QDECREF(lexer->token);
}
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