Applying pattern Regular Expression on C 작 성 자 : 김선영 메 일 : [email protected] 버 전 : 1.04 Copyright by SunYoung Kim

Applying patternApplying pattern

Regular Expression on CRegular Expression on C

작 성 자 : 김선영

메 일 : [email protected]

버 전 : 1.04

Copyright by SunYoung Kim

Copyright by SunYoung Kim <sunyzero (at) gmail (dot) com>

PrefacePreface

Regular Expression ( 정규표현식 ) 의 약칭 REGEX

string pattern 은 문자열의 조합되는 규칙

meta charater 는 다른 의미를 수식하는 문자

Pro*C 는 Oracle. 사의 상표입니다 .


Why needs?Why needs? short term transaction

DB 내부에서 데이터에 변경을 가하면 , 트랜잭션에 소모되는 시간이 길어진다 .

대용량 데이터를 다루는 경우라면 bottle-neck 이 될 가능성이 커진다 .

conclusion

되도록이면 데이터 가공은 프로시저보다 외부에서 하는 것이 좋다 .

통계수치상으로 볼때 데이터의 90% 이상은 텍스트 데이터이다 .

텍스트 처리는 정규표현식을 사용하는 것이 확장성에서 유용하다 .


REGEX on CREGEX on C POSIX style

표준화 작업의 산물

호환성이 높음

직관적이며 다른 언어와 API 가 비슷함

BSD style

BSD 초기 방식의 API (old fashion)

PCRE(Perl Compatible Regular Expression)

perl 확장 포함

perl 관련 라이브러리 필요


APIAPI pattern buffer : regex_t

패턴을 테스트하고 사용하기 위한 공간

regcomp(3)

정규표현식을 패턴 버퍼로 컴파일 ( 메모리 할당과정 발생 )

regerror(3)

패턴버퍼 컴파일 에러 보고

regexec(3)

패턴에 문자열 적용

regfree(3)

패턴버퍼 해제 ( 메모리 할당 해제 )


API: regcompAPI: regcomp int regcomp(regex_t *preg, const char *regex, int cflags)

regex_t *preg : 패턴버퍼

const char *regex : 컴파일할 패턴 문자열

int cflags : 컴파일 플래그

» REG_EXTENDED : POSIX 확장 정규표현식 사용

» REG_ICASE : 대소문자 무시

» REG_NOSUB : 서브스트링을 무시

» REG_NEWLINE: [...], [^...] 등이 New line 과는 매칭하지 않음 ( 라인단위 매칭 )

return value : 0 ( 성공 ), 이외의 값 ( 실패 )


API: regerrorAPI: regerror size_t regerror(int errcode, const regex_t *preg, char *errbuf, size_t err

buf_size)

int errcode : regcomp() 가 에러발생시 반환값


char *errbuf : 에러를 출력해줄 버퍼

size_t errbuf_size : errbuf 인수의 크기 (Byte)

return value : errbuf 에 출력한 에러메시지의 크기

if ((ret = regcomp(&re_expr, p_regex_str, REG_EXTENDED|REG_NEWLINE))){

regerror(ret, &re_expr, errbuf, sizeof(errbuf));

printf("Error regcomp() : %s\n", errbuf);

/* 에러처리 */

}




/* 에러처리 */

}


API: regexecAPI: regexec int regexec(const regex_t *preg, const char *string, size_t nmatch, re

gmatch_t pmatch[], int eflag)


char *string : 패턴 매칭할 대상 문자열

size_t nmatch : 매칭테이블 pmatch 배열의 개수

regmatch_t pmatch[] : 패턴 매칭 결과의 offset 을 저장해줄 매칭 테이블

eflags

» REG_NOTBOL: (not beginning-of-line) 라인 시작 패턴인 ^ 을 사용못함

» REG_NOTEOL: (not end-of-line) 라인 마지막 패턴인 $ 를 사용못함

return value : 0 ( 성공 ), 이외의 값 ( 실패 )


API: regexecAPI: regexec regmatch_t 타입의 형태 : <regex.h> 에 선언됨

typedef struct {

regoff_t rm_so;

regoff_t rm_eo;

} regmatch_t;

typedef struct {

regoff_t rm_so;

regoff_t rm_eo;

} regmatch_t;


API: regfreeAPI: regfree void regfree(regex_t *preg)



Example of REGEXExample of REGEX Usage : ./posix_regex [dest_string pattern_string]

#define MAX_EXPR_SUB_MATCH 5

#define DEFAULT_REGEX_STR "(</.+>).* "

#define DEFAULT_DEST_STR "<center>align to center</center> \

align to left New Line "

int main(int argc, char **argv) {

int i, ret;

char *p_regex_str; /* pattern string */

char *p_dest_str; /* destination string to apply pattern */

regex_t re_expr; /* POSIX REGEX pattern buffer */

regmatch_t rm_matchtab[MAX_EXPR_SUB_MATCH]; /* matching table*/

char errbuf[0xff];


#define DEFAULT_REGEX_STR "(</.+>).* "

#define DEFAULT_DEST_STR "<center>align to center</center> \

align to left New Line "


int i, ret;

char *p_regex_str; /* pattern string */

char *p_dest_str; /* destination string to apply pattern */

regex_t re_expr; /* POSIX REGEX pattern buffer */

regmatch_t rm_matchtab[MAX_EXPR_SUB_MATCH]; /* matching table*/

char errbuf[0xff];


Example of REGEX (con't)Example of REGEX (con't)

if (argc != 3) {

printf("Using default string!!\n");

printf("* Dest str : %s\n", DEFAULT_DEST_STR);

printf("* Regex str: %s\n", DEFAULT_REGEX_STR);

p_dest_str = strdup(DEFAULT_DEST_STR);

p_regex_str = strdup(DEFAULT_REGEX_STR);

} else {

p_dest_str = strdup(argv[1]); p_regex_str = strdup(argv[2]);

}




exit(EXIT_FAILURE);

}

if (argc != 3) {

printf("Using default string!!\n");

printf("* Dest str : %s\n", DEFAULT_DEST_STR);

printf("* Regex str: %s\n", DEFAULT_REGEX_STR);

p_dest_str = strdup(DEFAULT_DEST_STR);

p_regex_str = strdup(DEFAULT_REGEX_STR);

} else {

p_dest_str = strdup(argv[1]); p_regex_str = strdup(argv[2]);

}




exit(EXIT_FAILURE);

}



printf("regcomp : %s\n", p_regex_str);

memset(rm_matchtab, 0x00, sizeof(rm_matchtab));

if (regexec(&re_expr, p_dest_str, MAX_EXPR_SUB_MATCH, rm_matchtab, 0)) {

printf("fail to match\n");

} else {

printf("* All Match offset : (%d -> %d), len(%d) : %.*s\n",

rm_matchtab[0].rm_so, rm_matchtab[0].rm_eo,

rm_matchtab[0].rm_eo - rm_matchtab[0].rm_so,


&p_dest_str[rm_matchtab[0].rm_so]);

printf("regcomp : %s\n", p_regex_str);


if (regexec(&re_expr, p_dest_str, MAX_EXPR_SUB_MATCH, rm_matchtab, 0)) {

printf("fail to match\n");

} else {

printf("* All Match offset : (%d -> %d), len(%d) : %.*s\n",

rm_matchtab[0].rm_so, rm_matchtab[0].rm_eo,



&p_dest_str[rm_matchtab[0].rm_so]);



for (i=1; i<MAX_EXPR_SUB_MATCH; i++) {

if (rm_matchtab[i].rm_so == -1) break;

printf("* Submatch[%d] offset : (%d -> %d), len(%d) : %.*s\n",i,

rm_matchtab[i].rm_so, rm_matchtab[i].rm_eo,

rm_matchtab[i].rm_eo - rm_matchtab[i].rm_so,


&p_dest_str[rm_matchtab[i].rm_so]);

} /* end: for */

} /* end: else */

regfree(&re_expr); /* freeing pattern buffer memory */

return 0;

}

for (i=1; i<MAX_EXPR_SUB_MATCH; i++) {

if (rm_matchtab[i].rm_so == -1) break;

printf("* Submatch[%d] offset : (%d -> %d), len(%d) : %.*s\n",i,

rm_matchtab[i].rm_so, rm_matchtab[i].rm_eo,



&p_dest_str[rm_matchtab[i].rm_so]);

} /* end: for */

} /* end: else */

regfree(&re_expr); /* freeing pattern buffer memory */

return 0;

}


Example of REGEX (con't)Example of REGEX (con't) execution

Todo: URL 으로부터 hostname 과 URI 를 분리하는 것을 실습해봅시다

$ ./posix_regex

Using default string!!

* Dest str:<center>align to center</center> align to left New Line 

* Regex str: (</.+>).* 

regcomp : (</.+>).* 

* All Match offset:(23->66),len(43):</center> align to left New Line 

* Sub Match offset:(23->62),len(39):</center> align to left New Line 

$ ./posix_regex.exe http://news.naver.com/news/read.php "http://([^/]+)(.*)"

regcomp : http://([^/]+)(.*)

* All Match offset : (0 -> 35), len(35) : http://news.naver.com/news/read.php

* Submatch[1] offset : (7 -> 21), len(14) : news.naver.com

* Submatch[2] offset : (21 -> 35), len(14) : /news/read.php

$ ./posix_regex

Using default string!!

* Dest str:<center>align to center</center> align to left New Line 

* Regex str: (</.+>).* 

regcomp : (</.+>).* 

* All Match offset:(23->66),len(43):</center> align to left New Line 

* Sub Match offset:(23->62),len(39):</center> align to left New Line 

$ ./posix_regex.exe http://news.naver.com/news/read.php "http://([^/]+)(.*)"

regcomp : http://([^/]+)(.*)

* All Match offset : (0 -> 35), len(35) : http://news.naver.com/news/read.php

* Submatch[1] offset : (7 -> 21), len(14) : news.naver.com

* Submatch[2] offset : (21 -> 35), len(14) : /news/read.php


apply to Pro*C: raw dataapply to Pro*C: raw data 배치 처리할 데이터

# Raw data seqeunce: [Name] [Age] [Gender] [LOCALE]

--------------- KOR --------------

Korean staff list

YeongHee Lee| 25| Female| Korea

Hoon Kim, 29, Male, Pusan Korea

--------------- USA --------------

Steve, 29, Male, USA

Ken Jacobs, 48, Male,birmingham USA

Dave Roberts, 32, Male, New York USA

--------------- JAP --------------

Rikako, 42, Female, Nagano Japan

Lily, 35, Female,Osaka Japan

--------------- CHI --------------

Xiangping, 32, Male ,HongKong China

Chao Jien, 41, Male|HongKong China

# Raw data seqeunce: [Name] [Age] [Gender] [LOCALE]

--------------- KOR --------------

Korean staff list

YeongHee Lee| 25| Female| Korea

Hoon Kim, 29, Male, Pusan Korea

--------------- USA --------------

Steve, 29, Male, USA

Ken Jacobs, 48, Male,birmingham USA

Dave Roberts, 32, Male, New York USA

--------------- JAP --------------

Rikako, 42, Female, Nagano Japan

Lily, 35, Female,Osaka Japan

--------------- CHI --------------

Xiangping, 32, Male ,HongKong China

Chao Jien, 41, Male|HongKong China


apply to Pro*C: schemeapply to Pro*C: scheme DB scheme

WHENEVER SQLERROR CONTINUE;

DROP SEQUENCE SEQ_EMPLIST;

CREATE SEQUENCE SEQ_EMPLIST START WITH 1 INCREMENT BY 1 NOCYCLE NOCACHE;

DROP TABLE EMPLIST CASCADE CONSTRAINTS;

CREATE TABLE EMPLIST (

SNO NUMBER(5),

NAME VARCHAR(30),

GENDER NUMBER(1),

AGE NUMBER(3),

LOCALE VARCHAR(20)

);

WHENEVER SQLERROR CONTINUE;

DROP SEQUENCE SEQ_EMPLIST;

CREATE SEQUENCE SEQ_EMPLIST START WITH 1 INCREMENT BY 1 NOCYCLE NOCACHE;

DROP TABLE EMPLIST CASCADE CONSTRAINTS;

CREATE TABLE EMPLIST (

SNO NUMBER(5),

NAME VARCHAR(30),

GENDER NUMBER(1),

AGE NUMBER(3),

LOCALE VARCHAR(20)

);


apply to Pro*Capply to Pro*C pr7_regex.c : (todo) 필터링한 결과를 DB insert 하는것이 목적

예제는 불완전 하므로 기능을 완성하도록 합시다 .

typedef struct my_record {

short sno; char name[30+1]; short gender; unsigned short age; char locale[20+1];

} MY_RECORD;

int set_record(MY_RECORD *, const char *, const regmatch_t *);

int insert_rec(const MY_RECORD *s);


#define DEF_FILENAME "regdata.txt"

#define REGEX_STR "^([a-zA-Z ]+)[|,]([0-9 ]+)[|,]([a-zA-Z ]+)[|,]+([a-zA-Z ]+)"


char *p_filename;

regex_t re_expr; /* posix regex patern buffer */

regmatch_t rm_matchtab[MAX_EXPR_SUB_MATCH]; /* pattern matching table */

int i, ret;

FILE *fp;

char errbuf[0xff], buf[0xff];

MY_RECORD a_rec;

typedef struct my_record {

short sno; char name[30+1]; short gender; unsigned short age; char locale[20+1];

} MY_RECORD;

int set_record(MY_RECORD *, const char *, const regmatch_t *);

int insert_rec(const MY_RECORD *s);


#define DEF_FILENAME "regdata.txt"

#define REGEX_STR "^([a-zA-Z ]+)[|,]([0-9 ]+)[|,]([a-zA-Z ]+)[|,]+([a-zA-Z ]+)"


char *p_filename;

regex_t re_expr; /* posix regex patern buffer */

regmatch_t rm_matchtab[MAX_EXPR_SUB_MATCH]; /* pattern matching table */

int i, ret;

FILE *fp;

char errbuf[0xff], buf[0xff];

MY_RECORD a_rec;


apply to Pro*C (con't)apply to Pro*C (con't) if (argc != 2) {

printf("Using default filename!\n");

p_filename = DEF_FILENAME;

} else {

p_filename = strdup(argv[1]);

}

if ((fp = fopen(p_filename, "r")) == NULL) {

perror("FAIL: fopen");

exit(EXIT_FAILURE);

}

if ((ret = regcomp(&re_expr, REGEX_STR, REG_EXTENDED|REG_NEWLINE))) {



exit(EXIT_FAILURE);

}

printf("regcomp : %s\n", REGEX_STR);

/* ( 연습 ) DB 연결을 만든다 */

if (argc != 2) {

printf("Using default filename!\n");

p_filename = DEF_FILENAME;

} else {

p_filename = strdup(argv[1]);

}

if ((fp = fopen(p_filename, "r")) == NULL) {

perror("FAIL: fopen");

exit(EXIT_FAILURE);

}

if ((ret = regcomp(&re_expr, REGEX_STR, REG_EXTENDED|REG_NEWLINE))) {



exit(EXIT_FAILURE);

}

printf("regcomp : %s\n", REGEX_STR);

/* ( 연습 ) DB 연결을 만든다 */


apply to Pro*C (con't)apply to Pro*C (con't) while (!feof(fp)) {

if (fgets(buf, sizeof(buf), fp) == NULL) break;


if (regexec(&re_expr, buf, MAX_EXPR_SUB_MATCH, rm_matchtab, 0)) {

printf("fail to match: (%.30s ...)\n", buf);

} else {

if (set_record(&a_rec, buf, rm_matchtab)) {/* inser to db */

fprintf(stderr,"[%s:%d] FAIL: set_record()\n", __FILE__, __LINE__);

break;

}

if (insert_rec(&a_rec)) {

fprintf(stderr,"[%s:%d] FAIL: insert_rec()\n", __FILE__, __LINE__);

break;

}

EXEC SQL COMMIT;

} /* end: else */

} /* end: while */

while (!feof(fp)) {

if (fgets(buf, sizeof(buf), fp) == NULL) break;


if (regexec(&re_expr, buf, MAX_EXPR_SUB_MATCH, rm_matchtab, 0)) {

printf("fail to match: (%.30s ...)\n", buf);

} else {

if (set_record(&a_rec, buf, rm_matchtab)) {/* inser to db */

fprintf(stderr,"[%s:%d] FAIL: set_record()\n", __FILE__, __LINE__);

break;

}

if (insert_rec(&a_rec)) {

fprintf(stderr,"[%s:%d] FAIL: insert_rec()\n", __FILE__, __LINE__);

break;

}

EXEC SQL COMMIT;

} /* end: else */

} /* end: while */


apply to Pro*C (con't)apply to Pro*C (con't) regfree(&re_expr); /* free memory */

/* 연습 : commit 하면서 DB 연결 해제 */;

return 0;

} /* end: main() */

/* Macro: copy string indicated by the match table offset */

#define COPY_RMTAB(dest, src, matchtab) memcpy(dest, &src[matchtab.rm_so], \

matchtab.rm_eo - matchtab.rm_so); \

dest[matchtab.rm_eo - matchtab.rm_so] = 0x0

regfree(&re_expr); /* free memory */

/* 연습 : commit 하면서 DB 연결 해제 */;

return 0;

} /* end: main() */

/* Macro: copy string indicated by the match table offset */

#define COPY_RMTAB(dest, src, matchtab) memcpy(dest, &src[matchtab.rm_so], \

matchtab.rm_eo - matchtab.rm_so); \

dest[matchtab.rm_eo - matchtab.rm_so] = 0x0


apply to Pro*C (con't)apply to Pro*C (con't)int set_record(MY_RECORD *d, const char *sbuf, const regmatch_t *rmtab)

{

char buf[40]; /* temp. buffuer */

COPY_RMTAB(d->name, sbuf, rmtab[1]); /* name : 1st field => rmtab[1] */

COPY_RMTAB(buf, sbuf, rmtab[3]); /* gender: 3rd field => rmtab[3] */

if (strncmp(buf, "Male", 4) == 0) { /* with logical error! Why? */

d->gender = 1;

} else {

d->gender = 2; /* always '2'. !! */

}

COPY_RMTAB(buf, sbuf, rmtab[2]); d->age = atoi(buf);/* age:2nd field=>rmtab[2] */

COPY_RMTAB(d->locale, sbuf, rmtab[4]); /* locale: 4th field => rmtab[4] */

return 0;

} /* end: set_record() */

int insert_rec(const MY_RECORD *s) {

EXEC SQL INSERT INTO EMPLIST ... 생략 ...;

return SQLCODE;

} /* end: insert_rec() */

int set_record(MY_RECORD *d, const char *sbuf, const regmatch_t *rmtab)

{

char buf[40]; /* temp. buffuer */

COPY_RMTAB(d->name, sbuf, rmtab[1]); /* name : 1st field => rmtab[1] */

COPY_RMTAB(buf, sbuf, rmtab[3]); /* gender: 3rd field => rmtab[3] */

if (strncmp(buf, "Male", 4) == 0) { /* with logical error! Why? */

d->gender = 1;

} else {

d->gender = 2; /* always '2'. !! */

}

COPY_RMTAB(buf, sbuf, rmtab[2]); d->age = atoi(buf);/* age:2nd field=>rmtab[2] */

COPY_RMTAB(d->locale, sbuf, rmtab[4]); /* locale: 4th field => rmtab[4] */

return 0;

} /* end: set_record() */

int insert_rec(const MY_RECORD *s) {

EXEC SQL INSERT INTO EMPLIST ... 생략 ...;

return SQLCODE;

} /* end: insert_rec() */

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Applying pattern Regular Expression on C 작 성 자 : 김선영 메 일 : [email protected] 버 전 : 1.04 Copyright by SunYoung Kim