From 62815d85aed71eff7b6c3a524705180fb04f5d30 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:40:01 +0200 Subject: json: Redesign the callback to consume JSON values The classical way to structure parser and lexer is to have the client call the parser to get an abstract syntax tree, the parser call the lexer to get the next token, and the lexer call some function to get input characters. Another way to structure them would be to have the client feed characters to the lexer, the lexer feed tokens to the parser, and the parser feed abstract syntax trees to some callback provided by the client. This way is more easily integrated into an event loop that dispatches input characters as they arrive. Our JSON parser is kind of between the two. The lexer feeds tokens to a "streamer" instead of a real parser. The streamer accumulates tokens until it got the sequence of tokens that comprise a single JSON value (it counts curly braces and square brackets to decide). It feeds those token sequences to a callback provided by the client. The callback passes each token sequence to the parser, and gets back an abstract syntax tree. I figure it was done that way to make a straightforward recursive descent parser possible. "Get next token" becomes "pop the first token off the token sequence". Drawback: we need to store a complete token sequence. Each token eats 13 + input characters + malloc overhead bytes. Observations: 1. This is not the only way to use recursive descent. If we replaced "get next token" by a coroutine yield, we could do without a streamer. 2. The lexer reports errors by passing a JSON_ERROR token to the streamer. This communicates the offending input characters and their location, but no more. 3. The streamer reports errors by passing a null token sequence to the callback. The (already poor) lexical error information is thrown away. 4. Having the callback receive a token sequence duplicates the code to convert token sequence to abstract syntax tree in every callback. 5. Known bug: the streamer silently drops incomplete token sequences. This commit rectifies 4. by lifting the call of the parser from the callbacks into the streamer. Later commits will address 3. and 5. The lifting removes a bug from qjson.c's parse_json(): it passed a pointer to a non-null Error * in certain cases, as demonstrated by check-qjson.c. json_parser_parse() is now unused. It's a stupid wrapper around json_parser_parse_err(). Drop it, and rename json_parser_parse_err() to json_parser_parse(). Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-35-armbru@redhat.com> --- include/qapi/qmp/json-parser.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/qapi/qmp/json-parser.h') diff --git a/include/qapi/qmp/json-parser.h b/include/qapi/qmp/json-parser.h index 102f5c0068..a34209db7a 100644 --- a/include/qapi/qmp/json-parser.h +++ b/include/qapi/qmp/json-parser.h @@ -16,7 +16,6 @@ #include "qemu-common.h" -QObject *json_parser_parse(GQueue *tokens, va_list *ap); -QObject *json_parser_parse_err(GQueue *tokens, va_list *ap, Error **errp); +QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp); #endif -- cgit 1.4.1 From abe7c2067c21a89c6fd4cf2d8ba2fa37160d1d55 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:40:18 +0200 Subject: json: Make JSONToken opaque outside json-parser.c Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-52-armbru@redhat.com> --- include/qapi/qmp/json-parser.h | 4 ++++ include/qapi/qmp/json-streamer.h | 7 ------- qobject/json-parser.c | 19 +++++++++++++++++++ qobject/json-streamer.c | 8 +------- 4 files changed, 24 insertions(+), 14 deletions(-) (limited to 'include/qapi/qmp/json-parser.h') diff --git a/include/qapi/qmp/json-parser.h b/include/qapi/qmp/json-parser.h index a34209db7a..21b23d7bec 100644 --- a/include/qapi/qmp/json-parser.h +++ b/include/qapi/qmp/json-parser.h @@ -15,7 +15,11 @@ #define QEMU_JSON_PARSER_H #include "qemu-common.h" +#include "qapi/qmp/json-lexer.h" +typedef struct JSONToken JSONToken; + +JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr); QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp); #endif diff --git a/include/qapi/qmp/json-streamer.h b/include/qapi/qmp/json-streamer.h index d1d7fe2595..29950ac37c 100644 --- a/include/qapi/qmp/json-streamer.h +++ b/include/qapi/qmp/json-streamer.h @@ -16,13 +16,6 @@ #include "qapi/qmp/json-lexer.h" -typedef struct JSONToken { - int type; - int x; - int y; - char str[]; -} JSONToken; - typedef struct JSONMessageParser { void (*emit)(void *opaque, QObject *json, Error *err); diff --git a/qobject/json-parser.c b/qobject/json-parser.c index e9a9f937f3..a247875f14 100644 --- a/qobject/json-parser.c +++ b/qobject/json-parser.c @@ -26,6 +26,13 @@ #include "qapi/qmp/json-lexer.h" #include "qapi/qmp/json-streamer.h" +struct JSONToken { + JSONTokenType type; + int x; + int y; + char str[]; +}; + typedef struct JSONParserContext { Error *err; @@ -538,6 +545,18 @@ static QObject *parse_value(JSONParserContext *ctxt, va_list *ap) } } +JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr) +{ + JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1); + + token->type = type; + memcpy(token->str, tokstr->str, tokstr->len); + token->str[tokstr->len] = 0; + token->x = x; + token->y = y; + return token; +} + QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp) { JSONParserContext ctxt = { .buf = tokens }; diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c index 9210281a65..467bc29413 100644 --- a/qobject/json-streamer.c +++ b/qobject/json-streamer.c @@ -82,13 +82,7 @@ void json_message_process_token(JSONLexer *lexer, GString *input, goto out_emit; } - token = g_malloc(sizeof(JSONToken) + input->len + 1); - token->type = type; - memcpy(token->str, input->str, input->len); - token->str[input->len] = 0; - token->x = x; - token->y = y; - + token = json_token(type, x, y, input); parser->token_size += input->len; g_queue_push_tail(&parser->tokens, token); -- cgit 1.4.1 From 812ce33eadfc419795a5d1c7fe8f487fdfe2188c Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:40:19 +0200 Subject: qobject: Drop superfluous includes of qemu-common.h Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-53-armbru@redhat.com> --- include/qapi/qmp/json-parser.h | 1 - qobject/json-lexer.c | 1 - qobject/json-streamer.c | 1 - qobject/qbool.c | 1 - qobject/qlist.c | 1 - qobject/qnull.c | 1 - qobject/qnum.c | 1 - qobject/qobject.c | 1 - qobject/qstring.c | 1 - 9 files changed, 9 deletions(-) (limited to 'include/qapi/qmp/json-parser.h') diff --git a/include/qapi/qmp/json-parser.h b/include/qapi/qmp/json-parser.h index 21b23d7bec..55f75954c3 100644 --- a/include/qapi/qmp/json-parser.h +++ b/include/qapi/qmp/json-parser.h @@ -14,7 +14,6 @@ #ifndef QEMU_JSON_PARSER_H #define QEMU_JSON_PARSER_H -#include "qemu-common.h" #include "qapi/qmp/json-lexer.h" typedef struct JSONToken JSONToken; diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c index a728c32faa..06ec67dc45 100644 --- a/qobject/json-lexer.c +++ b/qobject/json-lexer.c @@ -12,7 +12,6 @@ */ #include "qemu/osdep.h" -#include "qemu-common.h" #include "qapi/qmp/json-lexer.h" #include "qapi/qmp/json-streamer.h" diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c index 467bc29413..da53e770e9 100644 --- a/qobject/json-streamer.c +++ b/qobject/json-streamer.c @@ -12,7 +12,6 @@ */ #include "qemu/osdep.h" -#include "qemu-common.h" #include "qapi/error.h" #include "qapi/qmp/json-lexer.h" #include "qapi/qmp/json-parser.h" diff --git a/qobject/qbool.c b/qobject/qbool.c index b58249925c..06dfc43498 100644 --- a/qobject/qbool.c +++ b/qobject/qbool.c @@ -13,7 +13,6 @@ #include "qemu/osdep.h" #include "qapi/qmp/qbool.h" -#include "qemu-common.h" /** * qbool_from_bool(): Create a new QBool from a bool diff --git a/qobject/qlist.c b/qobject/qlist.c index 37c1c167f1..b3274af88b 100644 --- a/qobject/qlist.c +++ b/qobject/qlist.c @@ -17,7 +17,6 @@ #include "qapi/qmp/qnum.h" #include "qapi/qmp/qstring.h" #include "qemu/queue.h" -#include "qemu-common.h" /** * qlist_new(): Create a new QList diff --git a/qobject/qnull.c b/qobject/qnull.c index f6f55f11ea..00870a1824 100644 --- a/qobject/qnull.c +++ b/qobject/qnull.c @@ -11,7 +11,6 @@ */ #include "qemu/osdep.h" -#include "qemu-common.h" #include "qapi/qmp/qnull.h" QNull qnull_ = { diff --git a/qobject/qnum.c b/qobject/qnum.c index 1501c82832..7012fc57f2 100644 --- a/qobject/qnum.c +++ b/qobject/qnum.c @@ -14,7 +14,6 @@ #include "qemu/osdep.h" #include "qapi/qmp/qnum.h" -#include "qemu-common.h" /** * qnum_from_int(): Create a new QNum from an int64_t diff --git a/qobject/qobject.c b/qobject/qobject.c index cf4b7e229e..878dd76e79 100644 --- a/qobject/qobject.c +++ b/qobject/qobject.c @@ -8,7 +8,6 @@ */ #include "qemu/osdep.h" -#include "qemu-common.h" #include "qapi/qmp/qbool.h" #include "qapi/qmp/qnull.h" #include "qapi/qmp/qnum.h" diff --git a/qobject/qstring.c b/qobject/qstring.c index 0f1510e792..1c6897df00 100644 --- a/qobject/qstring.c +++ b/qobject/qstring.c @@ -12,7 +12,6 @@ #include "qemu/osdep.h" #include "qapi/qmp/qstring.h" -#include "qemu-common.h" /** * qstring_new(): Create a new empty QString -- cgit 1.4.1 From 86cdf9ec8dec2763702cc52fa412d108a5dc9608 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:40:20 +0200 Subject: json: Clean up headers The JSON parser has three public headers, json-lexer.h, json-parser.h, json-streamer.h. They all contain stuff that is of no interest outside qobject/json-*.c. Collect the public interface in include/qapi/qmp/json-parser.h, and everything else in qobject/json-parser-int.h. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-54-armbru@redhat.com> --- include/qapi/qmp/json-lexer.h | 50 ------------------------------------- include/qapi/qmp/json-parser.h | 36 +++++++++++++++++++++------ include/qapi/qmp/json-streamer.h | 46 ---------------------------------- monitor.c | 2 +- qga/main.c | 2 +- qobject/json-lexer.c | 3 +-- qobject/json-parser-int.h | 54 ++++++++++++++++++++++++++++++++++++++++ qobject/json-parser.c | 4 +-- qobject/json-streamer.c | 4 +-- qobject/qjson.c | 2 +- tests/libqtest.c | 2 +- 11 files changed, 90 insertions(+), 115 deletions(-) delete mode 100644 include/qapi/qmp/json-lexer.h delete mode 100644 include/qapi/qmp/json-streamer.h create mode 100644 qobject/json-parser-int.h (limited to 'include/qapi/qmp/json-parser.h') diff --git a/include/qapi/qmp/json-lexer.h b/include/qapi/qmp/json-lexer.h deleted file mode 100644 index 508fc7bdaf..0000000000 --- a/include/qapi/qmp/json-lexer.h +++ /dev/null @@ -1,50 +0,0 @@ -/* - * JSON lexer - * - * Copyright IBM, Corp. 2009 - * - * Authors: - * Anthony Liguori - * - * 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. - * - */ - -#ifndef QEMU_JSON_LEXER_H -#define QEMU_JSON_LEXER_H - - -typedef enum json_token_type { - JSON_MIN = 100, - JSON_LCURLY = JSON_MIN, - JSON_RCURLY, - JSON_LSQUARE, - JSON_RSQUARE, - JSON_COLON, - JSON_COMMA, - JSON_INTEGER, - JSON_FLOAT, - JSON_KEYWORD, - JSON_STRING, - JSON_INTERP, - JSON_SKIP, - JSON_ERROR, - JSON_END_OF_INPUT, -} JSONTokenType; - -typedef struct JSONLexer { - int start_state, state; - GString *token; - int x, y; -} JSONLexer; - -void json_lexer_init(JSONLexer *lexer, bool enable_interpolation); - -void json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size); - -void json_lexer_flush(JSONLexer *lexer); - -void json_lexer_destroy(JSONLexer *lexer); - -#endif diff --git a/include/qapi/qmp/json-parser.h b/include/qapi/qmp/json-parser.h index 55f75954c3..7345a9bd5c 100644 --- a/include/qapi/qmp/json-parser.h +++ b/include/qapi/qmp/json-parser.h @@ -1,5 +1,5 @@ /* - * JSON Parser + * JSON Parser * * Copyright IBM, Corp. 2009 * @@ -11,14 +11,36 @@ * */ -#ifndef QEMU_JSON_PARSER_H -#define QEMU_JSON_PARSER_H +#ifndef QAPI_QMP_JSON_PARSER_H +#define QAPI_QMP_JSON_PARSER_H -#include "qapi/qmp/json-lexer.h" +typedef struct JSONLexer { + int start_state, state; + GString *token; + int x, y; +} JSONLexer; -typedef struct JSONToken JSONToken; +typedef struct JSONMessageParser { + void (*emit)(void *opaque, QObject *json, Error *err); + void *opaque; + va_list *ap; + JSONLexer lexer; + int brace_count; + int bracket_count; + GQueue tokens; + uint64_t token_size; +} JSONMessageParser; -JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr); -QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp); +void json_message_parser_init(JSONMessageParser *parser, + void (*emit)(void *opaque, QObject *json, + Error *err), + void *opaque, va_list *ap); + +void json_message_parser_feed(JSONMessageParser *parser, + const char *buffer, size_t size); + +void json_message_parser_flush(JSONMessageParser *parser); + +void json_message_parser_destroy(JSONMessageParser *parser); #endif diff --git a/include/qapi/qmp/json-streamer.h b/include/qapi/qmp/json-streamer.h deleted file mode 100644 index 29950ac37c..0000000000 --- a/include/qapi/qmp/json-streamer.h +++ /dev/null @@ -1,46 +0,0 @@ -/* - * JSON streaming support - * - * Copyright IBM, Corp. 2009 - * - * Authors: - * Anthony Liguori - * - * 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. - * - */ - -#ifndef QEMU_JSON_STREAMER_H -#define QEMU_JSON_STREAMER_H - -#include "qapi/qmp/json-lexer.h" - -typedef struct JSONMessageParser -{ - void (*emit)(void *opaque, QObject *json, Error *err); - void *opaque; - va_list *ap; - JSONLexer lexer; - int brace_count; - int bracket_count; - GQueue tokens; - uint64_t token_size; -} JSONMessageParser; - -void json_message_process_token(JSONLexer *lexer, GString *input, - JSONTokenType type, int x, int y); - -void json_message_parser_init(JSONMessageParser *parser, - void (*emit)(void *opaque, QObject *json, - Error *err), - void *opaque, va_list *ap); - -void json_message_parser_feed(JSONMessageParser *parser, - const char *buffer, size_t size); - -void json_message_parser_flush(JSONMessageParser *parser); - -void json_message_parser_destroy(JSONMessageParser *parser); - -#endif diff --git a/monitor.c b/monitor.c index 3dbdcb5190..021c11b1bf 100644 --- a/monitor.c +++ b/monitor.c @@ -58,7 +58,7 @@ #include "qapi/qmp/qnum.h" #include "qapi/qmp/qstring.h" #include "qapi/qmp/qjson.h" -#include "qapi/qmp/json-streamer.h" +#include "qapi/qmp/json-parser.h" #include "qapi/qmp/qlist.h" #include "qom/object_interfaces.h" #include "trace-root.h" diff --git a/qga/main.c b/qga/main.c index b74e1241ef..6d70242d05 100644 --- a/qga/main.c +++ b/qga/main.c @@ -18,7 +18,7 @@ #include #include #endif -#include "qapi/qmp/json-streamer.h" +#include "qapi/qmp/json-parser.h" #include "qapi/qmp/qdict.h" #include "qapi/qmp/qjson.h" #include "qapi/qmp/qstring.h" diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c index 06ec67dc45..e1745a3d95 100644 --- a/qobject/json-lexer.c +++ b/qobject/json-lexer.c @@ -12,8 +12,7 @@ */ #include "qemu/osdep.h" -#include "qapi/qmp/json-lexer.h" -#include "qapi/qmp/json-streamer.h" +#include "json-parser-int.h" #define MAX_TOKEN_SIZE (64ULL << 20) diff --git a/qobject/json-parser-int.h b/qobject/json-parser-int.h new file mode 100644 index 0000000000..ceaa890ec6 --- /dev/null +++ b/qobject/json-parser-int.h @@ -0,0 +1,54 @@ +/* + * JSON Parser + * + * Copyright IBM, Corp. 2009 + * + * Authors: + * Anthony Liguori + * + * 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. + * + */ + +#ifndef JSON_PARSER_INT_H +#define JSON_PARSER_INT_H + +#include "qapi/qmp/json-parser.h" + + +typedef enum json_token_type { + JSON_MIN = 100, + JSON_LCURLY = JSON_MIN, + JSON_RCURLY, + JSON_LSQUARE, + JSON_RSQUARE, + JSON_COLON, + JSON_COMMA, + JSON_INTEGER, + JSON_FLOAT, + JSON_KEYWORD, + JSON_STRING, + JSON_INTERP, + JSON_SKIP, + JSON_ERROR, + JSON_END_OF_INPUT, +} JSONTokenType; + +typedef struct JSONToken JSONToken; + +/* json-lexer.c */ +void json_lexer_init(JSONLexer *lexer, bool enable_interpolation); +void json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size); +void json_lexer_flush(JSONLexer *lexer); +void json_lexer_destroy(JSONLexer *lexer); + +/* json-streamer.c */ +void json_message_process_token(JSONLexer *lexer, GString *input, + JSONTokenType type, int x, int y); + +/* json-parser.c */ +JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr); +QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp); + +#endif diff --git a/qobject/json-parser.c b/qobject/json-parser.c index a247875f14..7449684f1c 100644 --- a/qobject/json-parser.c +++ b/qobject/json-parser.c @@ -22,9 +22,7 @@ #include "qapi/qmp/qnull.h" #include "qapi/qmp/qnum.h" #include "qapi/qmp/qstring.h" -#include "qapi/qmp/json-parser.h" -#include "qapi/qmp/json-lexer.h" -#include "qapi/qmp/json-streamer.h" +#include "json-parser-int.h" struct JSONToken { JSONTokenType type; diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c index da53e770e9..47dd7ea576 100644 --- a/qobject/json-streamer.c +++ b/qobject/json-streamer.c @@ -13,9 +13,7 @@ #include "qemu/osdep.h" #include "qapi/error.h" -#include "qapi/qmp/json-lexer.h" -#include "qapi/qmp/json-parser.h" -#include "qapi/qmp/json-streamer.h" +#include "json-parser-int.h" #define MAX_TOKEN_SIZE (64ULL << 20) #define MAX_TOKEN_COUNT (2ULL << 20) diff --git a/qobject/qjson.c b/qobject/qjson.c index b9ccae2c2a..db36101f3b 100644 --- a/qobject/qjson.c +++ b/qobject/qjson.c @@ -13,7 +13,7 @@ #include "qemu/osdep.h" #include "qapi/error.h" -#include "qapi/qmp/json-streamer.h" +#include "qapi/qmp/json-parser.h" #include "qapi/qmp/qjson.h" #include "qapi/qmp/qbool.h" #include "qapi/qmp/qdict.h" diff --git a/tests/libqtest.c b/tests/libqtest.c index 5973a67652..d635c5bea0 100644 --- a/tests/libqtest.c +++ b/tests/libqtest.c @@ -24,7 +24,7 @@ #include "qemu-common.h" #include "qemu/cutils.h" #include "qapi/error.h" -#include "qapi/qmp/json-streamer.h" +#include "qapi/qmp/json-parser.h" #include "qapi/qmp/qdict.h" #include "qapi/qmp/qjson.h" #include "qapi/qmp/qlist.h" -- cgit 1.4.1