From 2975abb487a54b49246646db9aa40ee6d1beaa97 Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@redhat.com>
Date: Wed, 27 Jul 2016 07:35:08 +0200
Subject: [PATCH 10/16] qjson: Convert to parser to recursive descent
RH-Author: Markus Armbruster <armbru@redhat.com>
Message-id: <1469604913-12442-12-git-send-email-armbru@redhat.com>
Patchwork-id: 71474
O-Subject: [RHEL-7.3 qemu-kvm PATCH v2 10/15] qjson: Convert to parser to recursive descent
Bugzilla: 1276036
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
We backtrack in parse_value(), even though JSON is LL(1) and thus can
be parsed by straightforward recursive descent. Do exactly that.
Based on an almost-correct patch from Paolo Bonzini.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1448486613-17634-10-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit d538b25543f4db026bb435066e2403a542522c40)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Conflicts:
qobject/json-parser.c
Straighforward conflicts because lacking commit fc48ffc "qobject: Use
'bool' for qbool", we still use qbool_from_int(), and we lack commit
e549e71 "json-parser: Accept 'null' in QMP".
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
qobject/json-parser.c | 163 ++++++++++++++------------------------------------
1 file changed, 46 insertions(+), 117 deletions(-)
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 79f4173..b242fba 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -266,23 +266,6 @@ static QObject *parser_context_peek_token(JSONParserContext *ctxt)
return token;
}
-static JSONParserContext parser_context_save(JSONParserContext *ctxt)
-{
- JSONParserContext saved_ctxt = {0};
- saved_ctxt.tokens.pos = ctxt->tokens.pos;
- saved_ctxt.tokens.count = ctxt->tokens.count;
- saved_ctxt.tokens.buf = ctxt->tokens.buf;
- return saved_ctxt;
-}
-
-static void parser_context_restore(JSONParserContext *ctxt,
- JSONParserContext saved_ctxt)
-{
- ctxt->tokens.pos = saved_ctxt.tokens.pos;
- ctxt->tokens.count = saved_ctxt.tokens.count;
- ctxt->tokens.buf = saved_ctxt.tokens.buf;
-}
-
static void tokens_append_from_iter(QObject *obj, void *opaque)
{
JSONParserContext *ctxt = opaque;
@@ -334,7 +317,6 @@ static void parser_context_free(JSONParserContext *ctxt)
static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap)
{
QObject *key = NULL, *token = NULL, *value, *peek;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
@@ -372,7 +354,6 @@ static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap)
return 0;
out:
- parser_context_restore(ctxt, saved_ctxt);
qobject_decref(key);
return -1;
@@ -382,16 +363,9 @@ static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
{
QDict *dict = NULL;
QObject *token, *peek;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
token = parser_context_pop_token(ctxt);
- if (token == NULL) {
- goto out;
- }
-
- if (token_get_type(token) != JSON_LCURLY) {
- goto out;
- }
+ assert(token && token_get_type(token) == JSON_LCURLY);
dict = qdict_new();
@@ -435,7 +409,6 @@ static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
return QOBJECT(dict);
out:
- parser_context_restore(ctxt, saved_ctxt);
QDECREF(dict);
return NULL;
}
@@ -444,16 +417,9 @@ static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
{
QList *list = NULL;
QObject *token, *peek;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
token = parser_context_pop_token(ctxt);
- if (token == NULL) {
- goto out;
- }
-
- if (token_get_type(token) != JSON_LSQUARE) {
- goto out;
- }
+ assert(token && token_get_type(token) == JSON_LSQUARE);
list = qlist_new();
@@ -507,107 +473,70 @@ static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
return QOBJECT(list);
out:
- parser_context_restore(ctxt, saved_ctxt);
QDECREF(list);
return NULL;
}
static QObject *parse_keyword(JSONParserContext *ctxt)
{
- QObject *token, *ret;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
+ QObject *token;
const char *val;
token = parser_context_pop_token(ctxt);
- if (token == NULL) {
- goto out;
- }
-
- if (token_get_type(token) != JSON_KEYWORD) {
- goto out;
- }
-
+ assert(token && token_get_type(token) == JSON_KEYWORD);
val = token_get_value(token);
if (!strcmp(val, "true")) {
- ret = QOBJECT(qbool_from_int(true));
+ return QOBJECT(qbool_from_int(true));
} else if (!strcmp(val, "false")) {
- ret = QOBJECT(qbool_from_int(false));
- } else {
- parse_error(ctxt, token, "invalid keyword '%s'", val);
- goto out;
+ return QOBJECT(qbool_from_int(false));
}
-
- return ret;
-
-out:
- parser_context_restore(ctxt, saved_ctxt);
-
+ parse_error(ctxt, token, "invalid keyword '%s'", val);
return NULL;
}
static QObject *parse_escape(JSONParserContext *ctxt, va_list *ap)
{
- QObject *token = NULL, *obj;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
+ QObject *token;
const char *val;
if (ap == NULL) {
- goto out;
+ return NULL;
}
token = parser_context_pop_token(ctxt);
- if (token == NULL) {
- goto out;
- }
-
- if (token_get_type(token) != JSON_ESCAPE) {
- goto out;
- }
-
+ assert(token && token_get_type(token) == JSON_ESCAPE);
val = token_get_value(token);
if (!strcmp(val, "%p")) {
- obj = va_arg(*ap, QObject *);
+ return va_arg(*ap, QObject *);
} else if (!strcmp(val, "%i")) {
- obj = QOBJECT(qbool_from_int(va_arg(*ap, int)));
+ return QOBJECT(qbool_from_int(va_arg(*ap, int)));
} else if (!strcmp(val, "%d")) {
- obj = QOBJECT(qint_from_int(va_arg(*ap, int)));
+ return QOBJECT(qint_from_int(va_arg(*ap, int)));
} else if (!strcmp(val, "%ld")) {
- obj = QOBJECT(qint_from_int(va_arg(*ap, long)));
+ return QOBJECT(qint_from_int(va_arg(*ap, long)));
} else if (!strcmp(val, "%lld") ||
!strcmp(val, "%I64d")) {
- obj = QOBJECT(qint_from_int(va_arg(*ap, long long)));
+ return QOBJECT(qint_from_int(va_arg(*ap, long long)));
} else if (!strcmp(val, "%s")) {
- obj = QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
+ return QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
} else if (!strcmp(val, "%f")) {
- obj = QOBJECT(qfloat_from_double(va_arg(*ap, double)));
- } else {
- goto out;
+ return QOBJECT(qfloat_from_double(va_arg(*ap, double)));
}
-
- return obj;
-
-out:
- parser_context_restore(ctxt, saved_ctxt);
-
return NULL;
}
static QObject *parse_literal(JSONParserContext *ctxt)
{
- QObject *token, *obj;
- JSONParserContext saved_ctxt = parser_context_save(ctxt);
+ QObject *token;
token = parser_context_pop_token(ctxt);
- if (token == NULL) {
- goto out;
- }
+ assert(token);
switch (token_get_type(token)) {
case JSON_STRING:
- obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
- break;
+ return QOBJECT(qstring_from_escaped_str(ctxt, token));
case JSON_INTEGER: {
/* A possibility exists that this is a whole-valued float where the
* fractional part was left out due to being 0 (.0). It's not a big
@@ -626,46 +555,46 @@ static QObject *parse_literal(JSONParserContext *ctxt)
errno = 0; /* strtoll doesn't set errno on success */
value = strtoll(token_get_value(token), NULL, 10);
if (errno != ERANGE) {
- obj = QOBJECT(qint_from_int(value));
- break;
+ return QOBJECT(qint_from_int(value));
}
/* fall through to JSON_FLOAT */
}
case JSON_FLOAT:
/* FIXME dependent on locale */
- obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));
- break;
+ return QOBJECT(qfloat_from_double(strtod(token_get_value(token),
+ NULL)));
default:
- goto out;
+ abort();
}
-
- return obj;
-
-out:
- parser_context_restore(ctxt, saved_ctxt);
-
- return NULL;
}
static QObject *parse_value(JSONParserContext *ctxt, va_list *ap)
{
- QObject *obj;
+ QObject *token;
- obj = parse_object(ctxt, ap);
- if (obj == NULL) {
- obj = parse_array(ctxt, ap);
- }
- if (obj == NULL) {
- obj = parse_escape(ctxt, ap);
- }
- if (obj == NULL) {
- obj = parse_keyword(ctxt);
- }
- if (obj == NULL) {
- obj = parse_literal(ctxt);
+ token = parser_context_peek_token(ctxt);
+ if (token == NULL) {
+ parse_error(ctxt, NULL, "premature EOI");
+ return NULL;
}
- return obj;
+ switch (token_get_type(token)) {
+ case JSON_LCURLY:
+ return parse_object(ctxt, ap);
+ case JSON_LSQUARE:
+ return parse_array(ctxt, ap);
+ case JSON_ESCAPE:
+ return parse_escape(ctxt, ap);
+ case JSON_INTEGER:
+ case JSON_FLOAT:
+ case JSON_STRING:
+ return parse_literal(ctxt);
+ case JSON_KEYWORD:
+ return parse_keyword(ctxt);
+ default:
+ parse_error(ctxt, token, "expecting value");
+ return NULL;
+ }
}
QObject *json_parser_parse(QList *tokens, va_list *ap)
--
1.8.3.1