| /*------------------------------------------------------------------------- | |
| * 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) 2000-2023, PostgreSQL Global Development Group | |
| * | |
| * src/include/fe_utils/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_reset(ConditionalStack cstack); | |
| 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); | |