From f871ef74a5560377d541e6d94704f30bcbcdb779 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 12 Jun 2012 16:23:45 -0400
Subject: [PATCH] Minor code review for json.c.
Improve commenting, conform to project style for use of ++ etc.
No functional changes.
---
src/backend/utils/adt/json.c | 164 +++++++++++++++++++----------------
1 file changed, 91 insertions(+), 73 deletions(-)
diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 3d69e50e8e0..e79c2946d0c 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -25,9 +25,9 @@
#include "utils/json.h"
#include "utils/typcache.h"
-typedef enum
+typedef enum /* types of JSON values */
{
- JSON_VALUE_INVALID,
+ JSON_VALUE_INVALID, /* non-value tokens are reported as this */
JSON_VALUE_STRING,
JSON_VALUE_NUMBER,
JSON_VALUE_OBJECT,
@@ -37,17 +37,17 @@ typedef enum
JSON_VALUE_NULL
} JsonValueType;
-typedef struct
+typedef struct /* state of JSON lexer */
{
- char *input;
- char *token_start;
- char *token_terminator;
- JsonValueType token_type;
- int line_number;
- char *line_start;
+ char *input; /* whole string being parsed */
+ char *token_start; /* start of current token within input */
+ char *token_terminator; /* end of previous or current token */
+ JsonValueType token_type; /* type of current token, once it's known */
+ int line_number; /* current line number (counting from 1) */
+ char *line_start; /* start of current line within input (BROKEN!!) */
} JsonLexContext;
-typedef enum
+typedef enum /* states of JSON parser */
{
JSON_PARSE_VALUE, /* expecting a value */
JSON_PARSE_ARRAY_START, /* saw '[', expecting value or ']' */
@@ -58,17 +58,18 @@ typedef enum
JSON_PARSE_OBJECT_COMMA /* saw object ',', expecting next label */
} JsonParseState;
-typedef struct JsonParseStack
+typedef struct JsonParseStack /* the parser state has to be stackable */
{
JsonParseState state;
+ /* currently only need the state enum, but maybe someday more stuff */
} JsonParseStack;
-typedef enum
+typedef enum /* required operations on state stack */
{
- JSON_STACKOP_NONE,
- JSON_STACKOP_PUSH,
- JSON_STACKOP_PUSH_WITH_PUSHBACK,
- JSON_STACKOP_POP
+ JSON_STACKOP_NONE, /* no-op */
+ JSON_STACKOP_PUSH, /* push new JSON_PARSE_VALUE stack item */
+ JSON_STACKOP_PUSH_WITH_PUSHBACK, /* push, then rescan current token */
+ JSON_STACKOP_POP /* pop, or expect end of input if no stack */
} JsonStackOp;
static void json_validate_cstring(char *input);
@@ -78,17 +79,28 @@ static void json_lex_number(JsonLexContext *lex, char *s);
static void report_parse_error(JsonParseStack *stack, JsonLexContext *lex);
static void report_invalid_token(JsonLexContext *lex);
static char *extract_mb_char(char *s);
-static void composite_to_json(Datum composite, StringInfo result, bool use_line_feeds);
+static void composite_to_json(Datum composite, StringInfo result,
+ bool use_line_feeds);
static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
Datum *vals, bool *nulls, int *valcount,
TYPCATEGORY tcategory, Oid typoutputfunc,
bool use_line_feeds);
-static void array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds);
+static void array_to_json_internal(Datum array, StringInfo result,
+ bool use_line_feeds);
/* fake type category for JSON so we can distinguish it in datum_to_json */
#define TYPCATEGORY_JSON 'j'
/* letters appearing in numeric output that aren't valid in a JSON number */
#define NON_NUMERIC_LETTER "NnAaIiFfTtYy"
+/* chars to consider as part of an alphanumeric token */
+#define JSON_ALPHANUMERIC_CHAR(c) \
+ (((c) >= 'a' && (c) <= 'z') || \
+ ((c) >= 'A' && (c) <= 'Z') || \
+ ((c) >= '0' && (c) <= '9') || \
+ (c) == '_' || \
+ IS_HIGHBIT_SET(c))
+
+
/*
* Input.
*/
@@ -99,6 +111,7 @@ json_in(PG_FUNCTION_ARGS)
json_validate_cstring(text);
+ /* Internal representation is the same as text, for now */
PG_RETURN_TEXT_P(cstring_to_text(text));
}
@@ -108,6 +121,7 @@ json_in(PG_FUNCTION_ARGS)
Datum
json_out(PG_FUNCTION_ARGS)
{
+ /* we needn't detoast because text_to_cstring will handle that */
Datum txt = PG_GETARG_DATUM(0);
PG_RETURN_CSTRING(TextDatumGetCString(txt));
@@ -119,8 +133,8 @@ json_out(PG_FUNCTION_ARGS)
Datum
json_send(PG_FUNCTION_ARGS)
{
- StringInfoData buf;
text *t = PG_GETARG_TEXT_PP(0);
+ StringInfoData buf;
pq_begintypsend(&buf);
pq_sendtext(&buf, VARDATA_ANY(t), VARSIZE_ANY_EXHDR(t));
@@ -176,7 +190,7 @@ json_validate_cstring(char *input)
/* Set up parse stack. */
stacksize = 32;
- stacktop = palloc(sizeof(JsonParseStack) * stacksize);
+ stacktop = (JsonParseStack *) palloc(sizeof(JsonParseStack) * stacksize);
stack = stacktop;
stack->state = JSON_PARSE_VALUE;
@@ -212,8 +226,8 @@ redo:
stack->state = JSON_PARSE_ARRAY_NEXT;
else if (lex.token_start[0] == ']')
op = JSON_STACKOP_POP;
- else if (lex.token_start[0] == '['
- || lex.token_start[0] == '{')
+ else if (lex.token_start[0] == '[' ||
+ lex.token_start[0] == '{')
{
stack->state = JSON_PARSE_ARRAY_NEXT;
op = JSON_STACKOP_PUSH_WITH_PUSHBACK;
@@ -234,15 +248,15 @@ redo:
case JSON_PARSE_OBJECT_START:
if (lex.token_type == JSON_VALUE_STRING)
stack->state = JSON_PARSE_OBJECT_LABEL;
- else if (lex.token_type == JSON_VALUE_INVALID
- && lex.token_start[0] == '}')
+ else if (lex.token_type == JSON_VALUE_INVALID &&
+ lex.token_start[0] == '}')
op = JSON_STACKOP_POP;
else
report_parse_error(stack, &lex);
break;
case JSON_PARSE_OBJECT_LABEL:
- if (lex.token_type == JSON_VALUE_INVALID
- && lex.token_start[0] == ':')
+ if (lex.token_type == JSON_VALUE_INVALID &&
+ lex.token_start[0] == ':')
{
stack->state = JSON_PARSE_OBJECT_NEXT;
op = JSON_STACKOP_PUSH;
@@ -271,19 +285,21 @@ redo:
(int) stack->state);
}
- /* Push or pop the stack, if needed. */
+ /* Push or pop the state stack, if needed. */
switch (op)
{
case JSON_STACKOP_PUSH:
case JSON_STACKOP_PUSH_WITH_PUSHBACK:
- ++stack;
+ stack++;
if (stack >= &stacktop[stacksize])
{
+ /* Need to enlarge the stack. */
int stackoffset = stack - stacktop;
- stacksize = stacksize + 32;
- stacktop = repalloc(stacktop,
- sizeof(JsonParseStack) * stacksize);
+ stacksize += 32;
+ stacktop = (JsonParseStack *)
+ repalloc(stacktop,
+ sizeof(JsonParseStack) * stacksize);
stack = stacktop + stackoffset;
}
stack->state = JSON_PARSE_VALUE;
@@ -299,7 +315,7 @@ redo:
report_parse_error(NULL, &lex);
return;
}
- --stack;
+ stack--;
break;
case JSON_STACKOP_NONE:
/* nothing to do */
@@ -321,15 +337,15 @@ json_lex(JsonLexContext *lex)
while (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r')
{
if (*s == '\n')
- ++lex->line_number;
- ++s;
+ lex->line_number++;
+ s++;
}
lex->token_start = s;
/* Determine token type. */
- if (strchr("{}[],:", s[0]))
+ if (strchr("{}[],:", s[0]) != NULL)
{
- /* strchr() doesn't return false on a NUL input. */
+ /* strchr() is willing to match a zero byte, so test for that. */
if (s[0] == '\0')
{
/* End of string. */
@@ -373,17 +389,16 @@ json_lex(JsonLexContext *lex)
* whole word as an unexpected token, rather than just some
* unintuitive prefix thereof.
*/
- for (p = s; (*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z')
- || (*p >= '0' && *p <= '9') || *p == '_' || IS_HIGHBIT_SET(*p);
- ++p)
- ;
+ for (p = s; JSON_ALPHANUMERIC_CHAR(*p); p++)
+ /* skip */ ;
- /*
- * We got some sort of unexpected punctuation or an otherwise
- * unexpected character, so just complain about that one character.
- */
if (p == s)
{
+ /*
+ * We got some sort of unexpected punctuation or an otherwise
+ * unexpected character, so just complain about that one
+ * character.
+ */
lex->token_terminator = s + 1;
report_invalid_token(lex);
}
@@ -415,9 +430,9 @@ json_lex(JsonLexContext *lex)
static void
json_lex_string(JsonLexContext *lex)
{
- char *s = lex->token_start + 1;
+ char *s;
- for (s = lex->token_start + 1; *s != '"'; ++s)
+ for (s = lex->token_start + 1; *s != '"'; s++)
{
/* Per RFC4627, these characters MUST be escaped. */
if ((unsigned char) *s < 32)
@@ -437,7 +452,7 @@ json_lex_string(JsonLexContext *lex)
else if (*s == '\\')
{
/* OK, we have an escape character. */
- ++s;
+ s++;
if (*s == '\0')
{
lex->token_terminator = s;
@@ -448,7 +463,7 @@ json_lex_string(JsonLexContext *lex)
int i;
int ch = 0;
- for (i = 1; i <= 4; ++i)
+ for (i = 1; i <= 4; i++)
{
if (s[i] == '\0')
{
@@ -474,9 +489,9 @@ json_lex_string(JsonLexContext *lex)
/* Account for the four additional bytes we just parsed. */
s += 4;
}
- else if (!strchr("\"\\/bfnrt", *s))
+ else if (strchr("\"\\/bfnrt", *s) == NULL)
{
- /* Error out. */
+ /* Not a valid string escape, so error out. */
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for type json"),
@@ -527,12 +542,12 @@ json_lex_number(JsonLexContext *lex, char *s)
/* Part (2): parse main digit string. */
if (*s == '0')
- ++s;
+ s++;
else if (*s >= '1' && *s <= '9')
{
do
{
- ++s;
+ s++;
} while (*s >= '0' && *s <= '9');
}
else
@@ -541,14 +556,14 @@ json_lex_number(JsonLexContext *lex, char *s)
/* Part (3): parse optional decimal portion. */
if (*s == '.')
{
- ++s;
+ s++;
if (*s < '0' || *s > '9')
error = true;
else
{
do
{
- ++s;
+ s++;
} while (*s >= '0' && *s <= '9');
}
}
@@ -556,26 +571,29 @@ json_lex_number(JsonLexContext *lex, char *s)
/* Part (4): parse optional exponent. */
if (*s == 'e' || *s == 'E')
{
- ++s;
+ s++;
if (*s == '+' || *s == '-')
- ++s;
+ s++;
if (*s < '0' || *s > '9')
error = true;
else
{
do
{
- ++s;
+ s++;
} while (*s >= '0' && *s <= '9');
}
}
- /* Check for trailing garbage. */
- for (p = s; (*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z')
- || (*p >= '0' && *p <= '9') || *p == '_' || IS_HIGHBIT_SET(*p); ++p)
- ;
+ /*
+ * Check for trailing garbage. As in json_lex(), any alphanumeric stuff
+ * here should be considered part of the token for error-reporting
+ * purposes.
+ */
+ for (p = s; JSON_ALPHANUMERIC_CHAR(*p); p++)
+ error = true;
lex->token_terminator = p;
- if (p > s || error)
+ if (error)
report_invalid_token(lex);
}
@@ -597,7 +615,7 @@ report_parse_error(JsonParseStack *stack, JsonLexContext *lex)
lex->input),
errdetail("The input string ended unexpectedly.")));
- /* Work out the offending token. */
+ /* Separate out the offending token. */
toklen = lex->token_terminator - lex->token_start;
token = palloc(toklen + 1);
memcpy(token, lex->token_start, toklen);
@@ -680,14 +698,15 @@ extract_mb_char(char *s)
}
/*
- * Turn a scalar Datum into JSON. Hand off a non-scalar datum to
- * composite_to_json or array_to_json_internal as appropriate.
+ * Turn a scalar Datum into JSON, appending the string to "result".
+ *
+ * Hand off a non-scalar datum to composite_to_json or array_to_json_internal
+ * as appropriate.
*/
-static inline void
-datum_to_json(Datum val, bool is_null, StringInfo result, TYPCATEGORY tcategory,
- Oid typoutputfunc)
+static void
+datum_to_json(Datum val, bool is_null, StringInfo result,
+ TYPCATEGORY tcategory, Oid typoutputfunc)
{
-
char *outputstr;
if (is_null)
@@ -735,6 +754,7 @@ datum_to_json(Datum val, bool is_null, StringInfo result, TYPCATEGORY tcategory,
outputstr = OidOutputFunctionCall(typoutputfunc, val);
escape_json(result, outputstr);
pfree(outputstr);
+ break;
}
}
@@ -748,9 +768,8 @@ array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, Datum *vals,
bool *nulls, int *valcount, TYPCATEGORY tcategory,
Oid typoutputfunc, bool use_line_feeds)
{
-
int i;
- char *sep;
+ const char *sep;
Assert(dim < ndims);
@@ -797,7 +816,6 @@ array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds)
int count = 0;
Datum *elements;
bool *nulls;
-
int16 typlen;
bool typbyval;
char typalign,
@@ -852,7 +870,7 @@ composite_to_json(Datum composite, StringInfo result, bool use_line_feeds)
*tuple;
int i;
bool needsep = false;
- char *sep;
+ const char *sep;
sep = use_line_feeds ? ",\n " : ",";
--
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