variables.h

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/*
 * psql - the PostgreSQL interactive terminal
 *
 * Copyright (c) 2000-2016, PostgreSQL Global Development Group
 *
 * src/bin/psql/variables.h
 */
#ifndef VARIABLES_H
#define VARIABLES_H

/*
 * This implements a sort of variable repository. One could also think of it
 * as a cheap version of an associative array. In each one of these
 * datastructures you can store name/value pairs.  There can also be an
 * "assign hook" function that is called whenever the variable's value is
 * changed.
 *
 * An "unset" operation causes the hook to be called with newval == NULL.
 *
 * Note: if value == NULL then the variable is logically unset, but we are
 * keeping the struct around so as not to forget about its hook function.
 */
typedef void (*VariableAssignHook) (const char *newval);

struct _variable
{
    char       *name;
    char       *value;
    VariableAssignHook assign_hook;
    struct _variable *next;
};

typedef struct _variable *VariableSpace;

VariableSpace CreateVariableSpace(void);
const char *GetVariable(VariableSpace space, const char *name);

bool        ParseVariableBool(const char *value, const char *name);
int ParseVariableNum(const char *val,
                 int defaultval,
                 int faultval,
                 bool allowtrail);
int GetVariableNum(VariableSpace space,
               const char *name,
               int defaultval,
               int faultval,
               bool allowtrail);

void        PrintVariables(VariableSpace space);

bool        SetVariable(VariableSpace space, const char *name, const char *value);
bool        SetVariableAssignHook(VariableSpace space, const char *name, VariableAssignHook hook);
bool        SetVariableBool(VariableSpace space, const char *name);
bool        DeleteVariable(VariableSpace space, const char *name);

#endif   /* VARIABLES_H */