Add C solution

1 files changed, 240 insertions, 0 deletions

diff --git a/challenge-017/paulo-custodio/c/ch-2.c b/challenge-017/paulo-custodio/c/ch-2.c
new file mode 100644
index 0000000000..42776be8cd
--- /dev/null
+++ b/challenge-017/paulo-custodio/c/ch-2.c
@@ -0,0 +1,240 @@
+/*
+Challenge 017
+
+Task #2
+Create a script to parse URL and print the components of URL. According to
+Wiki page, the URL syntax is as below:
+
+scheme:[//[userinfo@]host[:port]]path[?query][#fragment]
+
+For example: jdbc://user:password@localhost:3306/pwc?profile=true#h1
+
+  scheme:   jdbc
+  userinfo: user:password
+  host:     localhost
+  port:     3306
+  path:     /pwc
+  query:    profile=true
+  fragment: h1
+*/
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#define STR_OR_NULL(str)    ((str) ? (str) : "")
+
+struct url {
+    char* scheme;
+    char* userinfo;
+    char* host;
+    char* port;
+    char* path;
+    char* query;
+    char* fragment;
+};
+
+void* check_mem(void* p) {
+    if (!p) {
+        fputs("Out of memory", stderr);
+        exit(EXIT_FAILURE);
+    }
+    return p;
+}
+
+char* strndup(const char* str, size_t len) {
+    char* ret = check_mem(malloc(len + 1));
+    strncpy(ret, str, len);
+    ret[len] = '\0';
+    return ret;
+}
+
+void url_init(struct url* url) {
+    memset(url, 0, sizeof(struct url));
+}
+
+void url_free(struct url* url) {
+    free(url->scheme);
+    free(url->userinfo);
+    free(url->host);
+    free(url->port);
+    free(url->path);
+    free(url->query);
+    free(url->fragment);
+}
+
+bool parse_word(const char** p) {
+    if (isalpha(**p) || **p == '_') {
+        (*p)++;
+        while (isalnum(**p) || strchr("_+-.", **p) != NULL)
+            (*p)++;
+        return true;
+    }
+    else
+        return false;
+}
+
+bool match(const char** p, char c) {
+    if (**p == c) {
+        (*p)++;
+        return true;
+    }
+    else
+        return false;
+}
+
+bool match_str(const char** p, const char* str) {
+    if (strncmp(*p, str, strlen(str)) == 0) {
+        (*p) += strlen(str);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool parse_scheme(const char** p, char** scheme) {
+    const char* p0 = *p;
+    *scheme = NULL;
+    if (parse_word(p) && match(p, ':')) {
+        *scheme = strndup(p0, *p - p0 - 1);
+        return true;
+    }
+    else {
+        *p = p0;
+        return false;
+    }
+}
+
+bool parse_password(const char** p) {
+    if (**p == ':') {
+        (*p)++;
+        while (**p != '\0' && **p != '@')
+            (*p)++;
+        return true;
+    }
+    else
+        return false;
+}
+
+bool parse_userinfo(const char** p, char** userinfo) {
+    const char* p0 = *p;
+    *userinfo = NULL;
+    if (!parse_word(p))
+        return false;
+    parse_password(p);
+    if (**p != '@') {
+        *p = p0;
+        return false;
+    }
+    *userinfo = strndup(p0, *p - p0);
+    (*p)++;
+    return true;
+}
+
+bool parse_port(const char** p, char** port) {
+    if (**p == ':') {
+        (*p)++;
+        const char* p1 = *p;
+        while (isdigit(**p))
+            (*p)++;
+        *port = strndup(p1, *p - p1);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool parse_user(const char** p, char** userinfo, char** host, char** port) {
+    const char* p0 = *p;
+    *userinfo = NULL;
+    *host = NULL;
+    *port = NULL;
+    if (!match_str(p, "//"))
+        return false;
+    parse_userinfo(p, userinfo);
+    const char* p1 = *p;
+    if (!parse_word(p)) {
+        free(*userinfo);
+        *userinfo = NULL;
+        *p = p0;
+        return false;
+    }
+    *host = strndup(p1, *p - p1);
+    parse_port(p, port);
+    return true;
+}
+
+bool parse_path(const char** p, char** path) {
+    const char* p0 = *p;
+    *path = NULL;
+    while (parse_word(p) || match(p, '/'))
+        ;
+    if (*p != p0) {
+        *path = strndup(p0, *p - p0);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool parse_query(const char** p, char** query) {
+    *query = NULL;
+    if (**p == '?') {
+        (*p)++;
+        const char* p1 = *p;
+        while (**p != '\0' && **p != '#')
+            (*p)++;
+        *query = strndup(p1, *p - p1);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool parse_fragment(const char** p, char** fragment) {
+    *fragment = NULL;
+    if (**p == '#') {
+        (*p)++;
+        const char* p1 = *p;
+        while (**p != '\0')
+            (*p)++;
+        *fragment = strndup(p1, *p - p1);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool url_parse(struct url* url, const char* text) {
+    url_init(url);
+    const char* p = text;
+    if (!parse_scheme(&p, &url->scheme))
+        return false;
+    parse_user(&p, &url->userinfo, &url->host, &url->port);
+    if (!parse_path(&p, &url->path))
+        return false;
+    parse_query(&p, &url->query);
+    parse_fragment(&p, &url->fragment);
+    return true;
+}
+
+int main() {
+    char line[BUFSIZ];
+    while (fgets(line, sizeof(line), stdin)) {
+        struct url url;
+        if (url_parse(&url, line)) {
+            printf("scheme:   %s\n", STR_OR_NULL(url.scheme));
+            printf("userinfo: %s\n", STR_OR_NULL(url.userinfo));
+            printf("host:     %s\n", STR_OR_NULL(url.host));
+            printf("port:     %s\n", STR_OR_NULL(url.port));
+            printf("path:     %s\n", STR_OR_NULL(url.path));
+            printf("query:    %s\n", STR_OR_NULL(url.query));
+            printf("fragment: %s\n", STR_OR_NULL(url.fragment));
+        }
+        else {
+            puts("invalid url");
+        }
+    }
+}