漢のUNIX XMLをJSONに変換するコードを書いてみよう（Vol.53掲載）
著者：後藤大地
今回は前回作ったサンプルコードをベースに、XMLデータをJSON（JavaScript Object Notation）形式に変換する例を紹介する。XMLデータをJSON形式に変換する、またはその逆を実施するのは需要の高い処理だ。今回紹介するのはサンプルレベルのコードだが、それなりに実用的なコードが書けることをわかってもらえるだろう。
記事本文掲載のシェルスクリプトマガジンvol.53は以下のリンク先でご購入できます。
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#include <stdio.h> #include <expat.h> static void XMLCALL begin(void *, const XML_Char*, const XML_Char**); static void XMLCALL end(void *, const XML_Char *); static int depth = 0; int main(int argc, char *argv[]) { char buf[BUFSIZ]; int len, done; XML_Parser parser = XML_ParserCreate(NULL); XML_SetElementHandler(parser, begin, end); do { len = fread(buf, 1, sizeof(buf), stdin); done = len < sizeof(buf); if (XML_Parse(parser, buf, (int)len, done) == XML_STATUS_ERROR) return 1; } while (!done); XML_ParserFree(parser); return 0; } static void XMLCALL begin(void *d, const XML_Char *name, const XML_Char **attr) { for (int i = 0; i < depth; i++) printf("→"); printf("%s\n", name); ++depth; } static void XMLCALL end(void *d, const XML_Char * name) { --depth; } |
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<?xml version="1.0" encoding="UTF-8"?> <document> <docgroup> <docinfo> <title><p>タイトル</p></title> <author><p>名前</p></author> <firstedition><p>編集開始日</p></firstedition> <lastmodified><p>編集終了日</p></lastmodified> </docinfo> <docgroup> <docinfo> <title><p>章タイトル</p></title> </docinfo> <p>説明1</p> <p>説明2</p> </docgroup> </docgroup> </document> |
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CC= cc RM= rm -f EXPAT= -lexpat LIBDIR= /usr/local/lib INCLUDEDIR= /usr/local/include CFLAGS= -I${INCLUDEDIR} -L${LIBDIR} ${EXPAT} SRC= xml2json.c OUT= xml2json build: ${CC} -o ${OUT} ${CFLAGS} ${SRC} clean: ${RM} ${OUT} |
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#include <stdio.h> #include <string.h> #include <expat.h> static void XMLCALL begin(void *, const XML_Char*, const XML_Char**); static void XMLCALL end(void *, const XML_Char *); static int depth = 0; static char *struct_elements[] = { "document", "docgroup", "docinfo" }; static char *key_elements[] = { "title", "author", "firstedition", "lastmodified" }; static char *value_elements[] = { "p", }; int main(int argc, char *argv[]) { char buf[BUFSIZ]; int len, done; XML_Parser parser = XML_ParserCreate(NULL); XML_SetElementHandler(parser, begin, end); do { len = fread(buf, 1, sizeof(buf), stdin); done = len < sizeof(buf); if (XML_Parse(parser, buf, (int)len, done) == XML_STATUS_ERROR) return 1; } while (!done); XML_ParserFree(parser); return 0; } static void XMLCALL begin(void *d, const XML_Char *name, const XML_Char **attr) { int len, done; done = 0; len = sizeof(struct_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(struct_elements[i], name)) { printf("構造化要素: %s\n", name); done = 1; } } len = sizeof(key_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(key_elements[i], name)) { printf("鍵要素: %s\n", name); done = 1; } } len = sizeof(value_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(value_elements[i], name)) { printf("値要素: %s\n", name); done = 1; } } ++depth; } static void XMLCALL end(void *d, const XML_Char * name) { --depth; } |
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#include <stdio.h> #include <string.h> #include <expat.h> static void XMLCALL begin(void *, const XML_Char*, const XML_Char**); static void XMLCALL end(void *, const XML_Char *); static char *struct_elements[] = { "document", "docgroup", "docinfo" }; static char *key_elements[] = { "title", "author", "firstedition", "lastmodified" }; static char *value_elements[] = { "p", }; static int depth = 0; static char *pre_element; int main(int argc, char *argv[]) { char buf[BUFSIZ]; int len, done; XML_Parser parser = XML_ParserCreate(NULL); XML_SetElementHandler(parser, begin, end); do { len = fread(buf, 1, sizeof(buf), stdin); done = len < sizeof(buf); if (XML_Parse(parser, buf, (int)len, done) == XML_STATUS_ERROR) return 1; } while (!done); XML_ParserFree(parser); return 0; } static void XMLCALL begin(void *d, const XML_Char *name, const XML_Char **attr) { int len, done; done = 0; len = sizeof(struct_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(struct_elements[i], name)) { if (0 == strcmp("document", name)) printf("{ "); for (int i = 0; i < depth; i++) printf("\t"); printf("\"%s\": {\n", name); done = 1; pre_element = struct_elements[i]; } } len = sizeof(key_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(key_elements[i], name)) { for (int i = 0; i < depth; i++) printf("\t"); printf("\"%s\":", name); done = 1; pre_element = key_elements[i]; } } int parent_is_key = 0; len = sizeof(value_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(value_elements[i], name)) { for (int j = 0, k = sizeof(key_elements) / sizeof(char*); j < k; j++) { if (key_elements[j] == pre_element) { parent_is_key = 1; } } if (parent_is_key) { printf("\"値\",\n"); } else { for (int i = 0; i < depth; i++) printf("\t"); printf("\"content\": \"値\",\n"); } done = 1; pre_element = value_elements[i]; } } if (!done) pre_element = NULL; ++depth; } static void XMLCALL end(void *d, const XML_Char * name) { int len, done; --depth; done = 0; len = sizeof(struct_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(struct_elements[i], name)) { if (0 == strcmp("document", name)) printf("}\n"); else { for (int i = 0; i < depth; i++) printf("\t"); printf("},\n"); } done = 1; } } len = sizeof(key_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(key_elements[i], name)) { done = 1; } } len = sizeof(value_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(value_elements[i], name)) { done = 1; } } } |
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#include <stdio.h> #include <string.h> #include <expat.h> static void XMLCALL begin(void *, const XML_Char*, const XML_Char**); static void XMLCALL end(void *, const XML_Char *); static void XMLCALL chardata(void *, const XML_Char *, int); static char *struct_elements[] = { "document", "docgroup", "docinfo" }; static char *key_elements[] = { "title", "author", "firstedition", "lastmodified" }; static char *value_elements[] = { "p", }; static int depth = 0; static char *pre_element; int main(int argc, char *argv[]) { char buf[BUFSIZ]; int len, done; XML_Parser parser = XML_ParserCreate(NULL); XML_SetElementHandler(parser, begin, end); XML_SetCharacterDataHandler(parser, chardata); do { len = fread(buf, 1, sizeof(buf), stdin); done = len < sizeof(buf); if (XML_Parse(parser, buf, (int)len, done) == XML_STATUS_ERROR) return 1; } while (!done); XML_ParserFree(parser); return 0; } static void XMLCALL begin(void *d, const XML_Char *name, const XML_Char **attr) { int len, done; done = 0; len = sizeof(struct_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(struct_elements[i], name)) { if (0 == strcmp("document", name)) printf("{ "); for (int i = 0; i < depth; i++) printf("\t"); printf("\"%s\": {\n", name); done = 1; pre_element = struct_elements[i]; } } len = sizeof(key_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(key_elements[i], name)) { for (int i = 0; i < depth; i++) printf("\t"); printf("\"%s\":", name); done = 1; pre_element = key_elements[i]; } } int parent_is_key = 0; len = sizeof(value_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(value_elements[i], name)) { for (int j = 0, k = sizeof(key_elements) / sizeof(char*); j < k; j++) { if (key_elements[j] == pre_element) { parent_is_key = 1; } } if (parent_is_key) { printf("\""); } else { for (int i = 0; i < depth; i++) printf("\t"); printf("\"content\": \""); } done = 1; pre_element = value_elements[i]; } } if (!done) pre_element = NULL; ++depth; } static void XMLCALL end(void *d, const XML_Char * name) { int len, done; --depth; done = 0; len = sizeof(struct_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(struct_elements[i], name)) { if (0 == strcmp("document", name)) printf("}\n"); else { for (int i = 0; i < depth; i++) printf("\t"); printf("},\n"); } done = 1; } } len = sizeof(key_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(key_elements[i], name)) { done = 1; } } len = sizeof(value_elements) / sizeof(char*); for (int i = 0; !done && i < len; i++) { if (0 == strcmp(value_elements[i], name)) { printf("\",\n"); done = 1; } } } static void chardata(void *data, const XML_Char *cdata, int len) { char *p; p = (char *)cdata; for (int i = 0; i < len; i++) if ('\n' != *p) putchar(*p++); } |