143 lines
4.4 KiB
C
143 lines
4.4 KiB
C
/****************************************************************************
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* libs/libc/string/lib_strtokr.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <string.h>
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: strtok_r
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*
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* Description:
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* The strtok_r() function is a reentrant version strtok().
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* Like strtok(), it parses a string into a sequence of
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* tokens. On the first call to strtok() the string to be
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* parsed should be specified in 'str'. In each subsequent
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* call that should parse the same string, 'str' should be
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* NULL.
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*
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* The 'saveptr' argument is a pointer to a char *
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* variable that is used internally by strtok_r() in
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* order to maintain context between successive calls
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* that parse the same string.
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*
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* On the first call to strtok_r(), 'str' should point to the
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* string to be parsed, and the value of 'saveptr' is
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* ignored. In subsequent calls, 'str' should be NULL, and
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* saveptr should be unchanged since the previous call.
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*
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* The 'delim' argument specifies a set of characters that
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* delimit the tokens in the parsed string. The caller
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* may specify different strings in delim in successive
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* calls that parse the same string.
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*
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* Each call to strtok_r() returns a pointer to a null-
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* terminated string containing the next token. This
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* string does not include the delimiting character. If
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* no more tokens are found, strtok_r() returns NULL.
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*
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* A sequence of two or more contiguous delimiter
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* characters in the parsed string is considered to be a
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* single delimiter. Delimiter characters at the start or
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* end of the string are ignored. The tokens returned by
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* strtok() are always non-empty strings.
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*
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* Returned Value:
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* strtok_r() returns a pointer to the next token, or NULL
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* if there are no more tokens.
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*
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****************************************************************************/
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FAR char *strtok_r(FAR char *str, FAR const char *delim, FAR char **saveptr)
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{
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FAR char *pbegin;
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FAR char *pend = NULL;
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/* Decide if we are starting a new string or continuing from
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* the point we left off.
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*/
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if (str)
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{
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pbegin = str;
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}
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else if (saveptr && *saveptr)
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{
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pbegin = *saveptr;
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}
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else
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{
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return NULL;
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}
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/* Find the beginning of the next token */
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for (;
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*pbegin && strchr(delim, *pbegin) != NULL;
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pbegin++);
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/* If we are at the end of the string with nothing
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* but delimiters found, then return NULL.
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*/
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if (!*pbegin)
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{
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return NULL;
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}
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/* Find the end of the token */
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for (pend = pbegin + 1;
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*pend && strchr(delim, *pend) == NULL;
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pend++);
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/* pend either points to the end of the string or to
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* the first delimiter after the string.
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*/
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if (*pend)
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{
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/* Turn the delimiter into a null terminator */
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*pend++ = '\0';
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}
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/* Save the pointer where we left off and return the
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* beginning of the token.
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*/
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if (saveptr)
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{
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*saveptr = pend;
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}
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return pbegin;
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}
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