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Code Issues Releases Wiki Activity

Remove jsonapi.c's lex_accept(). 

At first glance, this function seems useful, but it actually increases
the amount of code required rather than decreasing it. Inline the
logic into the callers instead; most callers don't use the 'lexeme'
argument for anything and as a result considerable simplification is
possible.

Along the way, fix the header comment for the nearby function
lex_expect(), which mislabeled it as lex_accept().

Patch by me, reviewed by David Steele, Mark Dilger, and Andrew
Dunstan.

Discussion: http://postgr.es/m/CA+TgmoYfOXhd27MUDGioVh6QtpD0C1K-f6ObSA10AWiHBAL5bA@mail.gmail.com
This commit is contained in:
Robert Haas 2020-01-17 14:06:41 -05:00
parent 11b5e3e35d
commit 530609aa42
1 changed files with 51 additions and 73 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

124
src/backend/utils/adt/jsonapi.c
View File

@ -69,44 +69,7 @@ lex_peek(JsonLexContext *lex)
}
/*
* lex_accept
*
* accept the look_ahead token and move the lexer to the next token if the
* look_ahead token matches the token parameter. In that case, and if required,
* also hand back the de-escaped lexeme.
*
* returns true if the token matched, false otherwise.
*/
static inline bool
lex_accept(JsonLexContext *lex, JsonTokenType token, char **lexeme)
{
if (lex->token_type == token)
{
if (lexeme != NULL)
{
if (lex->token_type == JSON_TOKEN_STRING)
{
if (lex->strval != NULL)
*lexeme = pstrdup(lex->strval->data);
}
else
{
int len = (lex->token_terminator - lex->token_start);
char *tokstr = palloc(len + 1);
memcpy(tokstr, lex->token_start, len);
tokstr[len] = '\0';
*lexeme = tokstr;
}
}
json_lex(lex);
return true;
}
return false;
}
/*
* lex_accept
* lex_expect
*
* move the lexer to the next token if the current look_ahead token matches
* the parameter token. Otherwise, report an error.
@ -114,7 +77,9 @@ lex_accept(JsonLexContext *lex, JsonTokenType token, char **lexeme)
static inline void
lex_expect(JsonParseContext ctx, JsonLexContext *lex, JsonTokenType token)
{
if (!lex_accept(lex, token, NULL))
if (lex_peek(lex) == token)
json_lex(lex);
else
report_parse_error(ctx, lex);
}
@ -260,12 +225,14 @@ json_count_array_elements(JsonLexContext *lex)
lex_expect(JSON_PARSE_ARRAY_START, &copylex, JSON_TOKEN_ARRAY_START);
if (lex_peek(&copylex) != JSON_TOKEN_ARRAY_END)
{
do
while (1)
{
count++;
parse_array_element(&copylex, &nullSemAction);
if (copylex.token_type != JSON_TOKEN_COMMA)
break;
json_lex(&copylex);
}
while (lex_accept(&copylex, JSON_TOKEN_COMMA, NULL));
}
lex_expect(JSON_PARSE_ARRAY_NEXT, &copylex, JSON_TOKEN_ARRAY_END);
@ -286,35 +253,41 @@ parse_scalar(JsonLexContext *lex, JsonSemAction *sem)
{
char *val = NULL;
json_scalar_action sfunc = sem->scalar;
char **valaddr;
JsonTokenType tok = lex_peek(lex);
valaddr = sfunc == NULL ? NULL : &val;
/* a scalar must be a string, a number, true, false, or null */
switch (tok)
if (tok != JSON_TOKEN_STRING && tok != JSON_TOKEN_NUMBER &&
tok != JSON_TOKEN_TRUE && tok != JSON_TOKEN_FALSE &&
tok != JSON_TOKEN_NULL)
report_parse_error(JSON_PARSE_VALUE, lex);
/* if no semantic function, just consume the token */
if (sfunc == NULL)
{
case JSON_TOKEN_TRUE:
lex_accept(lex, JSON_TOKEN_TRUE, valaddr);
break;
case JSON_TOKEN_FALSE:
lex_accept(lex, JSON_TOKEN_FALSE, valaddr);
break;
case JSON_TOKEN_NULL:
lex_accept(lex, JSON_TOKEN_NULL, valaddr);
break;
case JSON_TOKEN_NUMBER:
lex_accept(lex, JSON_TOKEN_NUMBER, valaddr);
break;
case JSON_TOKEN_STRING:
lex_accept(lex, JSON_TOKEN_STRING, valaddr);
break;
default:
report_parse_error(JSON_PARSE_VALUE, lex);
json_lex(lex);
return;
}
if (sfunc != NULL)
(*sfunc) (sem->semstate, val, tok);
/* extract the de-escaped string value, or the raw lexeme */
if (lex_peek(lex) == JSON_TOKEN_STRING)
{
if (lex->strval != NULL)
val = pstrdup(lex->strval->data);
}
else
{
int len = (lex->token_terminator - lex->token_start);
val = palloc(len + 1);
memcpy(val, lex->token_start, len);
val[len] = '\0';
}
/* consume the token */
json_lex(lex);
/* invoke the callback */
(*sfunc) (sem->semstate, val, tok);
}
static void
@ -330,14 +303,13 @@ parse_object_field(JsonLexContext *lex, JsonSemAction *sem)
json_ofield_action ostart = sem->object_field_start;
json_ofield_action oend = sem->object_field_end;
bool isnull;
char **fnameaddr = NULL;
JsonTokenType tok;
if (ostart != NULL || oend != NULL)
fnameaddr = &fname;
if (!lex_accept(lex, JSON_TOKEN_STRING, fnameaddr))
if (lex_peek(lex) != JSON_TOKEN_STRING)
report_parse_error(JSON_PARSE_STRING, lex);
if ((ostart != NULL || oend != NULL) && lex->strval != NULL)
fname = pstrdup(lex->strval->data);
json_lex(lex);
lex_expect(JSON_PARSE_OBJECT_LABEL, lex, JSON_TOKEN_COLON);
@ -387,16 +359,19 @@ parse_object(JsonLexContext *lex, JsonSemAction *sem)
*/
lex->lex_level++;
/* we know this will succeed, just clearing the token */
lex_expect(JSON_PARSE_OBJECT_START, lex, JSON_TOKEN_OBJECT_START);
Assert(lex_peek(lex) == JSON_TOKEN_OBJECT_START);
json_lex(lex);
tok = lex_peek(lex);
switch (tok)
{
case JSON_TOKEN_STRING:
parse_object_field(lex, sem);
while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
while (lex_peek(lex) == JSON_TOKEN_COMMA)
{
json_lex(lex);
parse_object_field(lex, sem);
}
break;
case JSON_TOKEN_OBJECT_END:
break;
@ -473,8 +448,11 @@ parse_array(JsonLexContext *lex, JsonSemAction *sem)
parse_array_element(lex, sem);
while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
while (lex_peek(lex) == JSON_TOKEN_COMMA)
{
json_lex(lex);
parse_array_element(lex, sem);
}
}
lex_expect(JSON_PARSE_ARRAY_NEXT, lex, JSON_TOKEN_ARRAY_END);