/*------------------------------------------------------------------------- * * char.c * Functions for the built-in type "char" (not to be confused with * bpchar, which is the SQL CHAR(n) type). * * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/utils/adt/char.c,v 1.48 2008/01/01 19:45:52 momjian Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include "libpq/pqformat.h" #include "utils/builtins.h" /***************************************************************************** * USER I/O ROUTINES * *****************************************************************************/ /* * charin - converts "x" to 'x' * * Note that an empty input string will implicitly be converted to \0. */ Datum charin(PG_FUNCTION_ARGS) { char *ch = PG_GETARG_CSTRING(0); PG_RETURN_CHAR(ch[0]); } /* * charout - converts 'x' to "x" * * Note that if the char value is \0, the resulting string will appear * to be empty (null-terminated after zero characters). So this is the * inverse of the charin() function for such data. */ Datum charout(PG_FUNCTION_ARGS) { char ch = PG_GETARG_CHAR(0); char *result = (char *) palloc(2); result[0] = ch; result[1] = '\0'; PG_RETURN_CSTRING(result); } /* * charrecv - converts external binary format to char * * The external representation is one byte, with no character set * conversion. This is somewhat dubious, perhaps, but in many * cases people use char for a 1-byte binary type. */ Datum charrecv(PG_FUNCTION_ARGS) { StringInfo buf = (StringInfo) PG_GETARG_POINTER(0); PG_RETURN_CHAR(pq_getmsgbyte(buf)); } /* * charsend - converts char to binary format */ Datum charsend(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); StringInfoData buf; pq_begintypsend(&buf); pq_sendbyte(&buf, arg1); PG_RETURN_BYTEA_P(pq_endtypsend(&buf)); } /***************************************************************************** * PUBLIC ROUTINES * *****************************************************************************/ /* * NOTE: comparisons are done as though char is unsigned (uint8). * Conversions to and from integer are done as though char is signed (int8). * * You wanted consistency? */ Datum chareq(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL(arg1 == arg2); } Datum charne(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL(arg1 != arg2); } Datum charlt(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL((uint8) arg1 < (uint8) arg2); } Datum charle(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL((uint8) arg1 } Datum chargt(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL((uint8) arg1 > (uint8) arg2); } Datum charge(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); char arg2 = PG_GETARG_CHAR(1); PG_RETURN_BOOL((uint8) arg1 >= (uint8) arg2); } Datum chartoi4(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); PG_RETURN_INT32((int32) ((int8) arg1)); } Datum i4tochar(PG_FUNCTION_ARGS) { int32 arg1 = PG_GETARG_INT32(0); if (arg1 < SCHAR_MIN || arg1 > SCHAR_MAX) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), errmsg("\"char\" out of range"))); PG_RETURN_CHAR((int8) arg1); } Datum text_char(PG_FUNCTION_ARGS) { text *arg1 = PG_GETARG_TEXT_P(0); char result; /* * An empty input string is converted to \0 (for consistency with charin). * If the input is longer than one character, the excess data is silently * discarded. */ if (VARSIZE(arg1) > VARHDRSZ) result = *(VARDATA(arg1)); else result = '\0'; PG_RETURN_CHAR(result); } Datum char_text(PG_FUNCTION_ARGS) { char arg1 = PG_GETARG_CHAR(0); text *result = palloc(VARHDRSZ + 1); /* * Convert \0 to an empty string, for consistency with charout (and * because the text stuff doesn't like embedded nulls all that well). */ if (arg1 != '\0') { SET_VARSIZE(result, VARHDRSZ + 1); *(VARDATA(result)) = arg1; } else SET_VARSIZE(result, VARHDRSZ); PG_RETURN_TEXT_P(result); }
