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authorMarkus Armbruster <armbru@redhat.com>2015-11-25 22:23:30 +0100
committerMarkus Armbruster <armbru@redhat.com>2015-11-26 10:06:57 +0100
commitd538b25543f4db026bb435066e2403a542522c40 (patch)
tree0a05e2bc185ea28e613ce0021188903ed597c719 /qobject
parentd2ca7c0b0d876cf0e219ae7a92252626b0913a28 (diff)
downloadqemu-arm-d538b25543f4db026bb435066e2403a542522c40.tar.gz
qjson: Convert to parser to recursive descent
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>
Diffstat (limited to 'qobject')
-rw-r--r--qobject/json-parser.c165
1 files changed, 47 insertions, 118 deletions
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index b57cac74af..60dd6243a6 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -265,23 +265,6 @@ 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;
@@ -333,7 +316,6 @@ 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) {
@@ -371,7 +353,6 @@ 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;
@@ -381,16 +362,9 @@ 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();
@@ -434,7 +408,6 @@ static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
return QOBJECT(dict);
out:
- parser_context_restore(ctxt, saved_ctxt);
QDECREF(dict);
return NULL;
}
@@ -443,16 +416,9 @@ 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();
@@ -506,109 +472,72 @@ 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_bool(true));
+ return QOBJECT(qbool_from_bool(true));
} else if (!strcmp(val, "false")) {
- ret = QOBJECT(qbool_from_bool(false));
+ return QOBJECT(qbool_from_bool(false));
} else if (!strcmp(val, "null")) {
- ret = qnull();
- } else {
- parse_error(ctxt, token, "invalid keyword '%s'", val);
- goto out;
+ return qnull();
}
-
- 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_bool(va_arg(*ap, int)));
+ return QOBJECT(qbool_from_bool(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
@@ -627,46 +556,46 @@ 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)