/*------------------------------------------------------------------------- * * value.h * interface for Value nodes * * * Copyright (c) 2003-2020, PostgreSQL Global Development Group * * src/include/nodes/value.h * *------------------------------------------------------------------------- */ #ifndef VALUE_H #define VALUE_H #include "nodes/nodes.h" /*---------------------- * Value node * * The same Value struct is used for five node types: T_Integer, * T_Float, T_String, T_BitString, T_Null. * * Integral values are actually represented by a machine integer, * but both floats and strings are represented as strings. * Using T_Float as the node type simply indicates that * the contents of the string look like a valid numeric literal. * * (Before Postgres 7.0, we used a double to represent T_Float, * but that creates loss-of-precision problems when the value is * ultimately destined to be converted to NUMERIC. Since Value nodes * are only used in the parsing process, not for runtime data, it's * better to use the more general representation.) * * Note that an integer-looking string will get lexed as T_Float if * the value is too large to fit in an 'int'. * * Nulls, of course, don't need the value part at all. *---------------------- */ typedef struct Value { NodeTag type; /* tag appropriately (eg. T_String) */ union ValUnion { int ival; /* machine integer */ char *str; /* string */ } val; } Value; #define intVal(v) (((Value *)(v))->val.ival) #define floatVal(v) atof(((Value *)(v))->val.str) #define strVal(v) (((Value *)(v))->val.str) extern Value *makeInteger(int i); extern Value *makeFloat(char *numericStr); extern Value *makeString(char *str); extern Value *makeBitString(char *str); #endif /* VALUE_H */

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