101 lines
3.6 KiB
C
101 lines
3.6 KiB
C
/*-------------------------------------------------------------------------
|
|
* A stack of automaton states to handle nested conditionals.
|
|
*
|
|
* This file describes a stack of automaton states which
|
|
* allow a manage nested conditionals.
|
|
*
|
|
* It is used by:
|
|
* - "psql" interpreter for handling \if ... \endif
|
|
* - "pgbench" interpreter for handling \if ... \endif
|
|
* - "pgbench" syntax checker to test for proper nesting
|
|
*
|
|
* The stack holds the state of enclosing conditionals (are we in
|
|
* a true branch? in a false branch? have we already encountered
|
|
* a true branch?) so that the interpreter knows whether to execute
|
|
* code and whether to evaluate conditions.
|
|
*
|
|
* Copyright (c) 2000-2021, PostgreSQL Global Development Group
|
|
*
|
|
* src/include/fe_utils/conditional.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef CONDITIONAL_H
|
|
#define CONDITIONAL_H
|
|
|
|
/*
|
|
* Possible states of a single level of \if block.
|
|
*/
|
|
typedef enum ifState
|
|
{
|
|
IFSTATE_NONE = 0, /* not currently in an \if block */
|
|
IFSTATE_TRUE, /* currently in an \if or \elif that is true
|
|
* and all parent branches (if any) are true */
|
|
IFSTATE_FALSE, /* currently in an \if or \elif that is false
|
|
* but no true branch has yet been seen, and
|
|
* all parent branches (if any) are true */
|
|
IFSTATE_IGNORED, /* currently in an \elif that follows a true
|
|
* branch, or the whole \if is a child of a
|
|
* false parent branch */
|
|
IFSTATE_ELSE_TRUE, /* currently in an \else that is true and all
|
|
* parent branches (if any) are true */
|
|
IFSTATE_ELSE_FALSE /* currently in an \else that is false or
|
|
* ignored */
|
|
} ifState;
|
|
|
|
/*
|
|
* The state of nested \ifs is stored in a stack.
|
|
*
|
|
* query_len is used to determine what accumulated text to throw away at the
|
|
* end of an inactive branch. (We could, perhaps, teach the lexer to not add
|
|
* stuff to the query buffer in the first place when inside an inactive branch;
|
|
* but that would be very invasive.) We also need to save and restore the
|
|
* lexer's parenthesis nesting depth when throwing away text. (We don't need
|
|
* to save and restore any of its other state, such as comment nesting depth,
|
|
* because a backslash command could never appear inside a comment or SQL
|
|
* literal.)
|
|
*/
|
|
typedef struct IfStackElem
|
|
{
|
|
ifState if_state; /* current state, see enum above */
|
|
int query_len; /* length of query_buf at last branch start */
|
|
int paren_depth; /* parenthesis depth at last branch start */
|
|
struct IfStackElem *next; /* next surrounding \if, if any */
|
|
} IfStackElem;
|
|
|
|
typedef struct ConditionalStackData
|
|
{
|
|
IfStackElem *head;
|
|
} ConditionalStackData;
|
|
|
|
typedef struct ConditionalStackData *ConditionalStack;
|
|
|
|
|
|
extern ConditionalStack conditional_stack_create(void);
|
|
|
|
extern void conditional_stack_destroy(ConditionalStack cstack);
|
|
|
|
extern int conditional_stack_depth(ConditionalStack cstack);
|
|
|
|
extern void conditional_stack_push(ConditionalStack cstack, ifState new_state);
|
|
|
|
extern bool conditional_stack_pop(ConditionalStack cstack);
|
|
|
|
extern ifState conditional_stack_peek(ConditionalStack cstack);
|
|
|
|
extern bool conditional_stack_poke(ConditionalStack cstack, ifState new_state);
|
|
|
|
extern bool conditional_stack_empty(ConditionalStack cstack);
|
|
|
|
extern bool conditional_active(ConditionalStack cstack);
|
|
|
|
extern void conditional_stack_set_query_len(ConditionalStack cstack, int len);
|
|
|
|
extern int conditional_stack_get_query_len(ConditionalStack cstack);
|
|
|
|
extern void conditional_stack_set_paren_depth(ConditionalStack cstack, int depth);
|
|
|
|
extern int conditional_stack_get_paren_depth(ConditionalStack cstack);
|
|
|
|
#endif /* CONDITIONAL_H */
|