/*-------------------------------------------------------------------------
*
* parse_node.c
* various routines that make nodes for querytrees
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/parser/parse_node.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "catalog/pg_type.h"
#include "mb/pg_wchar.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "utils/builtins.h"
#include "utils/int8.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
#include "utils/varbit.h"
static void pcb_error_callback(void *arg);
/*
* make_parsestate
* Allocate and initialize a new ParseState.
*
* Caller should eventually release the ParseState via free_parsestate().
*/
ParseState *
make_parsestate(ParseState *parentParseState)
{
ParseState *pstate;
pstate = palloc0(sizeof(ParseState));
pstate->parentParseState = parentParseState;
/* Fill in fields that don't start at null/false/zero */
pstate->p_next_resno = 1;
if (parentParseState)
{
pstate->p_sourcetext = parentParseState->p_sourcetext;
/* all hooks are copied from parent */
pstate->p_pre_columnref_hook = parentParseState->p_pre_columnref_hook;
pstate->p_post_columnref_hook = parentParseState->p_post_columnref_hook;
pstate->p_paramref_hook = parentParseState->p_paramref_hook;
pstate->p_coerce_param_hook = parentParseState->p_coerce_param_hook;
pstate->p_ref_hook_state = parentParseState->p_ref_hook_state;
}
return pstate;
}
/*
* free_parsestate
* Release a ParseState and any subsidiary resources.
*/
void
free_parsestate(ParseState *pstate)
{
/*
* Check that we did not produce too many resnos; at the very least we
* cannot allow more than 2^16, since that would exceed the range of a
* AttrNumber. It seems safest to use MaxTupleAttributeNumber.
*/
if (pstate->p_next_resno - 1 > MaxTupleAttributeNumber)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("target lists can have at most %d entries",
MaxTupleAttributeNumber)));
if (pstate->p_target_relation != NULL)
heap_close(pstate->p_target_relation, NoLock);
pfree(pstate);
}
/*
* parser_errposition
* Report a parse-analysis-time cursor position, if possible.
*
* This is expected to be used within an ereport() call. The return value
* is a dummy (always 0, in fact).
*
* The locations stored in raw parsetrees are byte offsets into the source
* string. We have to convert them to 1-based character indexes for reporting
* to clients. (We do things this way to avoid unnecessary overhead in the
* normal non-error case: computing character indexes would be much more
* expensive than storing token offsets.)
*/
int
parser_errposition(ParseState *pstate, int location)
{
int pos;
/* No-op if location was not provided */
if (location < 0)
return 0;
/* Can't do anything if source text is not available */
if (pstate == NULL || pstate->p_sourcetext == NULL)
return 0;
/* Convert offset to character number */
pos = pg_mbstrlen_with_len(pstate->p_sourcetext, location) + 1;
/* And pass it to the ereport mechanism */
return errposition(pos);
}
/*
* setup_parser_errposition_callback
* Arrange for non-parser errors to report an error position
*
* Sometimes the parser calls functions that aren't part of the parser
* subsystem and can't reasonably be passed a ParseState; yet we would
* like any errors thrown in those functions to be tagged with a parse
* error location. Use this function to set up an error context stack
* entry that will accomplish that. Usage pattern:
*
* declare a local variable "ParseCallbackState pcbstate"
* ...
* setup_parser_errposition_callback(&pcbstate, pstate, location);
* call function that might throw error;
* cancel_parser_errposition_callback(&pcbstate);
*/
void
setup_parser_errposition_callback(ParseCallbackState *pcbstate,
ParseState *pstate, int location)
{
/* Setup error traceback support for ereport() */
pcbstate->pstate = pstate;
pcbstate->location = location;
pcbstate->errcontext.callback = pcb_error_callback;
pcbstate->errcontext.arg = (void *) pcbstate;
pcbstate->errcontext.previous = error_context_stack;
error_context_stack = &pcbstate->errcontext;
}
/*
* Cancel a previously-set-up errposition callback.
*/
void
cancel_parser_errposition_callback(ParseCallbackState *pcbstate)
{
/* Pop the error context stack */
error_context_stack = pcbstate->errcontext.previous;
}
/*
* Error context callback for inserting parser error location.
*
* Note that this will be called for *any* error occurring while the
* callback is installed. We avoid inserting an irrelevant error location
* if the error is a query cancel --- are there any other important cases?
*/
static void
pcb_error_callback(void *arg)
{
ParseCallbackState *pcbstate = (ParseCallbackState *) arg;
if (geterrcode() != ERRCODE_QUERY_CANCELED)
(void) parser_errposition(pcbstate->pstate, pcbstate->location);
}
/*
* make_var
* Build a Var node for an attribute identified by RTE and attrno
*/
Var *
make_var(ParseState *pstate, RangeTblEntry *rte, int attrno, int location)
{
Var *result;
int vnum,
sublevels_up;
Oid vartypeid;
int32 type_mod;
vnum = RTERangeTablePosn(pstate, rte, &sublevels_up);
get_rte_attribute_type(rte, attrno, &vartypeid, &type_mod);
result = makeVar(vnum, attrno, vartypeid, type_mod, sublevels_up);
result->location = location;
return result;
}
/*
* transformArrayType()
* Identify the types involved in a subscripting operation
*
* On entry, arrayType/arrayTypmod identify the type of the input value
* to be subscripted (which could be a domain type). These are modified
* if necessary to identify the actual array type and typmod, and the
* array's element type is returned. An error is thrown if the input isn't
* an array type.
*/
Oid
transformArrayType(Oid *arrayType, int32 *arrayTypmod)
{
Oid origArrayType = *arrayType;
Oid elementType;
HeapTuple type_tuple_array;
Form_pg_type type_struct_array;
/*
* If the input is a domain, smash to base type, and extract the actual
* typmod to be applied to the base type. Subscripting a domain is an
* operation that necessarily works on the base array type, not the domain
* itself. (Note that we provide no method whereby the creator of a
* domain over an array type could hide its ability to be subscripted.)
*/
*arrayType = getBaseTypeAndTypmod(*arrayType, arrayTypmod);
/* Get the type tuple for the array */
type_tuple_array = SearchSysCache1(TYPEOID, ObjectIdGetDatum(*arrayType));
if (!HeapTupleIsValid(type_tuple_array))
elog(ERROR, "cache lookup failed for type %u", *arrayType);
type_struct_array = (Form_pg_type) GETSTRUCT(type_tuple_array);
/* needn't check typisdefined since this will fail anyway */
elementType = type_struct_array->typelem;
if (elementType == InvalidOid)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("cannot subscript type %s because it is not an array",
format_type_be(origArrayType))));
ReleaseSysCache(type_tuple_array);
return elementType;
}
/*
* transformArraySubscripts()
* Transform array subscripting. This is used for both
* array fetch and array assignment.
*
* In an array fetch, we are given a source array value and we produce an
* expression that represents the result of extracting a single array element
* or an array slice.
*
* In an array assignment, we are given a destination array value plus a
* source value that is to be assigned to a single element or a slice of
* that array. We produce an expression that represents the new array value
* with the source data inserted into the right part of the array.
*
* For both cases, if the source array is of a domain-over-array type,
* the result is of the base array type or its element type; essentially,
* we must fold a domain to its base type before applying subscripting.
*
* pstate Parse state
* arrayBase Already-transformed expression for the array as a whole
* arrayType OID of array's datatype (should match type of arrayBase,
* or be the base type of arrayBase's domain type)
* elementType OID of array's element type (fetch with transformArrayType,
* or pass InvalidOid to do it here)
* arrayTypMod typmod for the array (which is also typmod for the elements)
* indirection Untransformed list of subscripts (must not be NIL)
* assignFrom NULL for array fetch, else transformed expression for source.
*/
ArrayRef *
transformArraySubscripts(ParseState *pstate,
Node *arrayBase,
Oid arrayType,
Oid elementType,
int32 arrayTypMod,
List *indirection,
Node *assignFrom)
{
bool isSlice = false;
List *upperIndexpr = NIL;
List *lowerIndexpr = NIL;
ListCell *idx;
ArrayRef *aref;
/*
* Caller may or may not have bothered to determine elementType. Note
* that if the caller did do so, arrayType/arrayTypMod must be as
* modified by transformArrayType, ie, smash domain to base type.
*/
if (!OidIsValid(elementType))
elementType = transformArrayType(&arrayType, &arrayTypMod);
/*
* A list containing only single subscripts refers to a single array
* element. If any of the items are double subscripts (lower:upper), then
* the subscript expression means an array slice operation. In this case,
* we supply a default lower bound of 1 for any items that contain only a
* single subscript. We have to prescan the indirection list to see if
* there are any double subscripts.
*/
foreach(idx, indirection)
{
A_Indices *ai = (A_Indices *) lfirst(idx);
if (ai->lidx != NULL)
{
isSlice = true;
break;
}
}
/*
* Transform the subscript expressions.
*/
foreach(idx, indirection)
{
A_Indices *ai = (A_Indices *) lfirst(idx);
Node *subexpr;
Assert(IsA(ai, A_Indices));
if (isSlice)
{
if (ai->lidx)
{
subexpr = transformExpr(pstate, ai->lidx);
/* If it's not int4 already, try to coerce */
subexpr = coerce_to_target_type(pstate,
subexpr, exprType(subexpr),
INT4OID, -1,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST,
-1);
if (subexpr == NULL)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("array subscript must have type integer"),
parser_errposition(pstate, exprLocation(ai->lidx))));
}
else
{
/* Make a constant 1 */
subexpr = (Node *) makeConst(INT4OID,
-1,
sizeof(int32),
Int32GetDatum(1),
false,
true); /* pass by value */
}
lowerIndexpr = lappend(lowerIndexpr, subexpr);
}
subexpr = transformExpr(pstate, ai->uidx);
/* If it's not int4 already, try to coerce */
subexpr = coerce_to_target_type(pstate,
subexpr, exprType(subexpr),
INT4OID, -1,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST,
-1);
if (subexpr == NULL)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("array subscript must have type integer"),
parser_errposition(pstate, exprLocation(ai->uidx))));
upperIndexpr = lappend(upperIndexpr, subexpr);
}
/*
* If doing an array store, coerce the source value to the right type.
* (This should agree with the coercion done by transformAssignedExpr.)
*/
if (assignFrom != NULL)
{
Oid typesource = exprType(assignFrom);
Oid typeneeded = isSlice ? arrayType : elementType;
Node *newFrom;
newFrom = coerce_to_target_type(pstate,
assignFrom, typesource,
typeneeded, arrayTypMod,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST,
-1);
if (newFrom == NULL)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("array assignment requires type %s"
" but expression is of type %s",
format_type_be(typeneeded),
format_type_be(typesource)),
errhint("You will need to rewrite or cast the expression."),
parser_errposition(pstate, exprLocation(assignFrom))));
assignFrom = newFrom;
}
/*
* Ready to build the ArrayRef node.
*/
aref = makeNode(ArrayRef);
aref->refarraytype = arrayType;
aref->refelemtype = elementType;
aref->reftypmod = arrayTypMod;
aref->refupperindexpr = upperIndexpr;
aref->reflowerindexpr = lowerIndexpr;
aref->refexpr = (Expr *) arrayBase;
aref->refassgnexpr = (Expr *) assignFrom;
return aref;
}
/*
* make_const
*
* Convert a Value node (as returned by the grammar) to a Const node
* of the "natural" type for the constant. Note that this routine is
* only used when there is no explicit cast for the constant, so we
* have to guess what type is wanted.
*
* For string literals we produce a constant of type UNKNOWN ---- whose
* representation is the same as cstring, but it indicates to later type
* resolution that we're not sure yet what type it should be considered.
* Explicit "NULL" constants are also typed as UNKNOWN.
*
* For integers and floats we produce int4, int8, or numeric depending
* on the value of the number. XXX We should produce int2 as well,
* but additional cleanup is needed before we can do that; there are
* too many examples that fail if we try.
*/
Const *
make_const(ParseState *pstate, Value *value, int location)
{
Const *con;
Datum val;
int64 val64;
Oid typeid;
int typelen;
bool typebyval;
ParseCallbackState pcbstate;
switch (nodeTag(value))
{
case T_Integer:
val = Int32GetDatum(intVal(value));
typeid = INT4OID;
typelen = sizeof(int32);
typebyval = true;
break;
case T_Float:
/* could be an oversize integer as well as a float ... */
if (scanint8(strVal(value), true, &val64))
{
/*
* It might actually fit in int32. Probably only INT_MIN can
* occur, but we'll code the test generally just to be sure.
*/
int32 val32 = (int32) val64;
if (val64 == (int64) val32)
{
val = Int32GetDatum(val32);
typeid = INT4OID;
typelen = sizeof(int32);
typebyval = true;
}
else
{
val = Int64GetDatum(val64);
typeid = INT8OID;
typelen = sizeof(int64);
typebyval = FLOAT8PASSBYVAL; /* int8 and float8 alike */
}
}
else
{
/* arrange to report location if numeric_in() fails */
setup_parser_errposition_callback(&pcbstate, pstate, location);
val = DirectFunctionCall3(numeric_in,
CStringGetDatum(strVal(value)),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1));
cancel_parser_errposition_callback(&pcbstate);
typeid = NUMERICOID;
typelen = -1; /* variable len */
typebyval = false;
}
break;
case T_String:
/*
* We assume here that UNKNOWN's internal representation is the
* same as CSTRING
*/
val = CStringGetDatum(strVal(value));
typeid = UNKNOWNOID; /* will be coerced later */
typelen = -2; /* cstring-style varwidth type */
typebyval = false;
break;
case T_BitString:
/* arrange to report location if bit_in() fails */
setup_parser_errposition_callback(&pcbstate, pstate, location);
val = DirectFunctionCall3(bit_in,
CStringGetDatum(strVal(value)),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1));
cancel_parser_errposition_callback(&pcbstate);
typeid = BITOID;
typelen = -1;
typebyval = false;
break;
case T_Null:
/* return a null const */
con = makeConst(UNKNOWNOID,
-1,
-2,
(Datum) 0,
true,
false);
con->location = location;
return con;
default:
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(value));
return NULL; /* keep compiler quiet */
}
con = makeConst(typeid,
-1, /* typmod -1 is OK for all cases */
typelen,
val,
false,
typebyval);
con->location = location;
return con;
}