greenplumn read 源码
greenplumn read 代码
文件路径：/src/backend/nodes/read.c
/*-------------------------------------------------------------------------
*
* read.c
* routines to convert a string (legal ascii representation of node) back
* to nodes
*
* Portions Copyright (c) 2006-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/nodes/read.c
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
* Andrew Yu Nov 2, 1994 file creation
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include "common/string.h"
#include "nodes/pg_list.h"
#include "nodes/readfuncs.h"
#include "nodes/value.h"
/* Static state for pg_strtok */
static const char *pg_strtok_ptr = NULL;
static const char *pg_strtok_begin = NULL; /*CDB*/
/* State flag that determines how readfuncs.c should treat location fields */
#ifdef WRITE_READ_PARSE_PLAN_TREES
bool restore_location_fields = false;
#endif
static void nodeReadSkipThru(char closingDelimiter); /*CDB*/
/*
* Helper functions for saving current states and pg_strtok() another string
*
* External functions like ExtensibleNodeMethods->nodeRead() uses the
* pg_strtok_ptr information via pg_strtok() but the context could be binary
* (readfast.c), set_strtok_states() to pg_strtok() the string.
*/
void
save_strtok_states(const char ** save_ptr, const char ** save_begin)
{
*save_ptr = pg_strtok_ptr; /* point pg_strtok at the string to read */
*save_begin = pg_strtok_begin; /* CDB: save starting position for debug */
}
void
set_strtok_states(const char *ptr, const char *begin)
{
pg_strtok_ptr = ptr; /* point pg_strtok at the string to read */
pg_strtok_begin = begin; /* CDB: save starting position for debug */
}
/*
* stringToNode -
* builds a Node tree from its string representation (assumed valid)
*
* restore_loc_fields instructs readfuncs.c whether to restore location
* fields rather than set them to -1. This is currently only supported
* in builds with the WRITE_READ_PARSE_PLAN_TREES debugging flag set.
*/
static void *
stringToNodeInternal(const char *str, bool restore_loc_fields)
{
void *retval;
const char *save_strtok;
const char *save_begin = pg_strtok_begin;
#ifdef WRITE_READ_PARSE_PLAN_TREES
bool save_restore_location_fields;
#endif
/*
* We save and restore the pre-existing state of pg_strtok. This makes the
* world safe for re-entrant invocation of stringToNode, without incurring
* a lot of notational overhead by having to pass the next-character
* pointer around through all the readfuncs.c code.
*/
save_strtok = pg_strtok_ptr;
pg_strtok_ptr = str; /* point pg_strtok at the string to read */
pg_strtok_begin = str; /* CDB: save starting position for debug */
/*
* If enabled, likewise save/restore the location field handling flag.
*/
#ifdef WRITE_READ_PARSE_PLAN_TREES
save_restore_location_fields = restore_location_fields;
restore_location_fields = restore_loc_fields;
#endif
retval = nodeRead(NULL, 0); /* do the reading */
pg_strtok_ptr = save_strtok;
pg_strtok_begin = save_begin;
#ifdef WRITE_READ_PARSE_PLAN_TREES
restore_location_fields = save_restore_location_fields;
#endif
return retval;
}
/*
* Externally visible entry points
*/
void *
stringToNode(const char *str)
{
return stringToNodeInternal(str, false);
}
#ifdef WRITE_READ_PARSE_PLAN_TREES
void *
stringToNodeWithLocations(const char *str)
{
return stringToNodeInternal(str, true);
}
#endif
/*****************************************************************************
*
* the lisp token parser
*
*****************************************************************************/
/*
* pg_strtok --- retrieve next "token" from a string.
*
* Works kinda like strtok, except it never modifies the source string.
* (Instead of storing nulls into the string, the length of the token
* is returned to the caller.)
* Also, the rules about what is a token are hard-wired rather than being
* configured by passing a set of terminating characters.
*
* The string is assumed to have been initialized already by stringToNode.
*
* The rules for tokens are:
* * Whitespace (space, tab, newline) always separates tokens.
* * The characters '(', ')', '{', '}' form individual tokens even
* without any whitespace around them.
* * Otherwise, a token is all the characters up to the next whitespace
* or occurrence of one of the four special characters.
* * A backslash '\' can be used to quote whitespace or one of the four
* special characters, so that it is treated as a plain token character.
* Backslashes themselves must also be backslashed for consistency.
* Any other character can be, but need not be, backslashed as well.
* * If the resulting token is '<>' (with no backslash), it is returned
* as a non-NULL pointer to the token but with length == 0. Note that
* there is no other way to get a zero-length token.
*
* Returns a pointer to the start of the next token, and the length of the
* token (including any embedded backslashes!) in *length. If there are
* no more tokens, NULL and 0 are returned.
*
* NOTE: this routine doesn't remove backslashes; the caller must do so
* if necessary (see "debackslash").
*
* NOTE: prior to release 7.0, this routine also had a special case to treat
* a token starting with '"' as extending to the next '"'. This code was
* broken, however, since it would fail to cope with a string containing an
* embedded '"'. I have therefore removed this special case, and instead
* introduced rules for using backslashes to quote characters. Higher-level
* code should add backslashes to a string constant to ensure it is treated
* as a single token.
*/
const char *
pg_strtok(int *length)
{
const char *local_str; /* working pointer to string */
const char *ret_str; /* start of token to return */
local_str = pg_strtok_ptr;
while (*local_str == ' ' || *local_str == '\n' || *local_str == '\t')
local_str++;
if (*local_str == '\0')
{
*length = 0;
pg_strtok_ptr = local_str;
return NULL; /* no more tokens */
}
/*
* Now pointing at start of next token.
*/
ret_str = local_str;
if (*local_str == '(' || *local_str == ')' ||
*local_str == '{' || *local_str == '}')
{
/* special 1-character token */
local_str++;
}
else
{
/* Normal token, possibly containing backslashes */
while (*local_str != '\0' &&
*local_str != ' ' && *local_str != '\n' &&
*local_str != '\t' &&
*local_str != '(' && *local_str != ')' &&
*local_str != '{' && *local_str != '}')
{
if (*local_str == '\\' && local_str[1] != '\0')
local_str += 2;
else
local_str++;
}
}
*length = local_str - ret_str;
/* Recognize special case for "empty" token */
if (*length == 2 && ret_str[0] == '<' && ret_str[1] == '>')
*length = 0;
pg_strtok_ptr = local_str;
return ret_str;
}
/*
* debackslash -
* create a palloc'd string holding the given token.
* any protective backslashes in the token are removed.
*/
char *
debackslash(const char *token, int length)
{
char *result = palloc(length + 1);
char *ptr = result;
while (length > 0)
{
if (*token == '\\' && length > 1)
token++, length--;
*ptr++ = *token++;
length--;
}
*ptr = '\0';
return result;
}
#define RIGHT_PAREN (1000000 + 1)
#define LEFT_PAREN (1000000 + 2)
#define LEFT_BRACE (1000000 + 3)
#define OTHER_TOKEN (1000000 + 4)
/*
* nodeTokenType -
* returns the type of the node token contained in token.
* It returns one of the following valid NodeTags:
* T_Integer, T_Float, T_String, T_BitString
* and some of its own:
* RIGHT_PAREN, LEFT_PAREN, LEFT_BRACE, OTHER_TOKEN
*
* Assumption: the ascii representation is legal
*/
static NodeTag
nodeTokenType(const char *token, int length)
{
NodeTag retval;
const char *numptr;
int numlen;
/*
* Check if the token is a number
*/
numptr = token;
numlen = length;
if (*numptr == '+' || *numptr == '-')
numptr++, numlen--;
if ((numlen > 0 && isdigit((unsigned char) *numptr)) ||
(numlen > 1 && *numptr == '.' && isdigit((unsigned char) numptr[1])))
{
/*
* Yes. Figure out whether it is integral or float; this requires
* both a syntax check and a range check. strtoint() can do both for
* us. We know the token will end at a character that strtoint will
* stop at, so we do not need to modify the string.
*/
char *endptr;
errno = 0;
(void) strtoint(token, &endptr, 10);
if (endptr != token + length || errno == ERANGE)
return T_Float;
return T_Integer;
}
/*
* these three cases do not need length checks, since pg_strtok() will
* always treat them as single-byte tokens
*/
else if (*token == '(')
retval = LEFT_PAREN;
else if (*token == ')')
retval = RIGHT_PAREN;
else if (*token == '{')
retval = LEFT_BRACE;
else if (*token == '"' && length > 1 && token[length - 1] == '"')
retval = T_String;
else if (*token == 'b')
retval = T_BitString;
else
retval = OTHER_TOKEN;
return retval;
}
/*
* nodeRead -
* Slightly higher-level reader.
*
* This routine applies some semantic knowledge on top of the purely
* lexical tokenizer pg_strtok(). It can read
* * Value token nodes (integers, floats, or strings);
* * General nodes (via parseNodeString() from readfuncs.c);
* * Lists of the above;
* * Lists of integers or OIDs.
* The return value is declared void *, not Node *, to avoid having to
* cast it explicitly in callers that assign to fields of different types.
*
* External callers should always pass NULL/0 for the arguments. Internally
* a non-NULL token may be passed when the upper recursion level has already
* scanned the first token of a node's representation.
*
* We assume pg_strtok is already initialized with a string to read (hence
* this should only be invoked from within a stringToNode operation).
*/
void *
nodeRead(const char *token, int tok_len)
{
Node *result;
NodeTag type;
if (token == NULL) /* need to read a token? */
{
token = pg_strtok(&tok_len);
if (token == NULL) /* end of input */
return NULL;
}
type = nodeTokenType(token, tok_len);
switch ((int) type)
{
case LEFT_BRACE:
result = parseNodeString();
token = pg_strtok(&tok_len);
/*
* CDB: Check for extra fields left over following the ones that
* were consumed by the node reader function. If this tree was
* read from the catalog, it might have been stored by a future
* release which may have added fields that we don't know about.
*/
while (token &&
token[0] == ':')
{
/*
* Check for special :prereq tag that a future release may have
* inserted to tell us that the node's semantics are not
* downward compatible. The node reader function should have
* consumed any such tags for features that it supports. If a
* :prereq is left to be seen here, that means its feature isn't
* implemented in this release and we must reject the statement.
* The tag should be followed by a concise feature name or
* release id that can be shown to the user in an error message.
*/
if (tok_len == 7 &&
memcmp(token, ":prereq", 7) == 0)
{
token = pg_strtok(&tok_len);
token = debackslash(token, tok_len);
ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("This operation requires a feature "
"called \"%.*s\" which is not "
"supported in this version of %s.",
tok_len, token, PACKAGE_NAME)
));
}
/*
* Other extra fields can safely be ignored. They are assumed
* downward compatible unless a :prereq tag tells us otherwise.
*/
nodeReadSkip();
ereport(DEBUG2, (errmsg("nodeRead: unknown option '%.*s' ignored",
tok_len, token),
errdetail("Skipped '%.*s' at offset %d in %s",
(int)(pg_strtok_ptr - token), token,
(int)(token - pg_strtok_begin),
pg_strtok_begin)
));
token = pg_strtok(&tok_len);
}
if (token == NULL )
elog(ERROR, "did not find '}' at end of input node");
if (token[0] != '}')
elog(ERROR, "did not find '}' at end of input node, instead found %s",token);
break;
case LEFT_PAREN:
{
List *l = NIL;
/*----------
* Could be an integer list: (i int int ...)
* or an OID list: (o int int ...)
* or a list of nodes/values: (node node ...)
*----------
*/
token = pg_strtok(&tok_len);
if (token == NULL)
elog(ERROR, "unterminated List structure");
if (tok_len == 1 && token[0] == 'i')
{
/* List of integers */
for (;;)
{
int val;
char *endptr;
token = pg_strtok(&tok_len);
if (token == NULL)
elog(ERROR, "unterminated List structure");
if (token[0] == ')')
break;
val = (int) strtol(token, &endptr, 10);
if (endptr != token + tok_len)
elog(ERROR, "unrecognized integer: \"%.*s\"",
tok_len, token);
l = lappend_int(l, val);
}
}
else if (tok_len == 1 && token[0] == 'o')
{
/* List of OIDs */
for (;;)
{
Oid val;
char *endptr;
token = pg_strtok(&tok_len);
if (token == NULL)
elog(ERROR, "unterminated List structure");
if (token[0] == ')')
break;
val = (Oid) strtoul(token, &endptr, 10);
if (endptr != token + tok_len)
elog(ERROR, "unrecognized OID: \"%.*s\"",
tok_len, token);
l = lappend_oid(l, val);
}
}
else
{
/* List of other node types */
for (;;)
{
/* We have already scanned next token... */
if (token[0] == ')')
break;
l = lappend(l, nodeRead(token, tok_len));
token = pg_strtok(&tok_len);
if (token == NULL)
elog(ERROR, "unterminated List structure");
}
}
result = (Node *) l;
break;
}
case RIGHT_PAREN:
elog(ERROR, "unexpected right parenthesis");
result = NULL; /* keep compiler happy */
break;
case OTHER_TOKEN:
if (tok_len == 0)
{
/* must be "<>" --- represents a null pointer */
result = NULL;
}
else
{
elog(ERROR, "unrecognized token: \"%.*s\"", tok_len, token);
result = NULL; /* keep compiler happy */
}
break;
case T_Integer:
/*
* we know that the token terminates on a char atoi will stop at
*/
result = (Node *) makeInteger(atoi(token));
break;
case T_Float:
{
char *fval = (char *) palloc(tok_len + 1);
memcpy(fval, token, tok_len);
fval[tok_len] = '\0';
result = (Node *) makeFloat(fval);
}
break;
case T_String:
/* need to remove leading and trailing quotes, and backslashes */
result = (Node *) makeString(debackslash(token + 1, tok_len - 2));
break;
case T_BitString:
{
char *val = palloc(tok_len);
/* skip leading 'b' */
memcpy(val, token + 1, tok_len - 1);
val[tok_len - 1] = '\0';
result = (Node *) makeBitString(val);
break;
}
default:
elog(ERROR, "unrecognized node type: %d", (int) type);
result = NULL; /* keep compiler happy */
break;
}
return (void *) result;
}
/*
* nodeReadSkip
* Skips next item (a token, list or subtree).
*/
void
nodeReadSkip(void)
{
int tok_len;
const char *token = pg_strtok(&tok_len);
if (!token)
{
elog(ERROR, "did not find expected token");
return; /* not reached */
}
switch (*token)
{
case '{':
nodeReadSkipThru('}');
break;
case '(':
nodeReadSkipThru(')');
break;
case '}':
case ')':
elog(ERROR, "did not find expected token, instead found %s", token);
return; /* not reached */
default:
break;
}
} /* nodeReadSkip */
/*
* nodeReadSkipThru
* Skips one or more tokens, lists or subtrees up to and including
* the specified matching delimiter.
*/
void
nodeReadSkipThru(char closingDelimiter)
{
for (;;)
{
int tok_len;
const char *token = pg_strtok(&tok_len);
if (!token)
{
elog(ERROR, "did not find '%c' as expected", closingDelimiter);
return; /* not reached */
}
switch (*token)
{
case '{':
nodeReadSkipThru('}');
break;
case '(':
nodeReadSkipThru(')');
break;
case '}':
case ')':
if (*token != closingDelimiter)
elog(ERROR, "did not find '%c' as expected, instead found %s",
closingDelimiter, token);
return; /* not reached */
default:
break;
}
}
} /* nodeReadSkipThru */
/*
* pg_strtok_peek_fldname
* Peeks at the token that will be returned by the next call to
* pg_strtok and returns true if it is, case-sensitively,
* :fldname
*/
bool
pg_strtok_peek_fldname(const char *fldname)
{
const char *bp = pg_strtok_ptr;
const char *cp;
if (!bp)
return false;
/* trim leading whitespace */
if (*bp <= ' ')
{
while (*bp == ' ' || *bp == '\n' || *bp == '\t')
bp++;
pg_strtok_ptr = bp;
}
if (*bp != ':')
return false;
cp = bp+1;
while (*fldname != '\0' &&
*fldname == *cp)
{
cp++;
fldname++;
}
if (*fldname != '\0')
return false;
if (*cp == ' ' ||
*cp == '\n' ||
*cp == '\t' ||
*cp == '(' ||
*cp == ')' ||
*cp == '{' ||
*cp == '}' ||
*cp == '\0')
return true;
return false;
} /* pg_strtok_peek_fldname */
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