Data commit

Task/Mad-Libs/C/mad-libs.c

@@ -0,0 +1,145 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define err(...) fprintf(stderr, ## __VA_ARGS__), exit(1)
+
+/* We create a dynamic string with a few functions which make modifying
+ * the string and growing a bit easier */
+typedef struct {
+    char *data;
+    size_t alloc;
+    size_t length;
+} dstr;
+
+inline int dstr_space(dstr *s, size_t grow_amount)
+{
+    return s->length + grow_amount < s->alloc;
+}
+
+int dstr_grow(dstr *s)
+{
+    s->alloc *= 2;
+    char *attempt = realloc(s->data, s->alloc);
+
+    if (!attempt) return 0;
+    else s->data = attempt;
+
+    return 1;
+}
+
+dstr* dstr_init(const size_t to_allocate)
+{
+    dstr *s = malloc(sizeof(dstr));
+    if (!s) goto failure;
+
+    s->length = 0;
+    s->alloc  = to_allocate;
+    s->data   = malloc(s->alloc);
+
+    if (!s->data) goto failure;
+
+    return s;
+
+failure:
+    if (s->data) free(s->data);
+    if (s) free(s);
+    return NULL;
+}
+
+void dstr_delete(dstr *s)
+{
+    if (s->data) free(s->data);
+    if (s) free(s);
+}
+
+dstr* readinput(FILE *fd)
+{
+    static const size_t buffer_size = 4096;
+    char buffer[buffer_size];
+
+    dstr *s = dstr_init(buffer_size);
+    if (!s) goto failure;
+
+    while (fgets(buffer, buffer_size, fd)) {
+        while (!dstr_space(s, buffer_size))
+            if (!dstr_grow(s)) goto failure;
+
+        strncpy(s->data + s->length, buffer, buffer_size);
+        s->length += strlen(buffer);
+    }
+
+    return s;
+
+failure:
+    dstr_delete(s);
+    return NULL;
+}
+
+void dstr_replace_all(dstr *story, const char *replace, const char *insert)
+{
+    const size_t replace_l = strlen(replace);
+    const size_t insert_l  = strlen(insert);
+    char *start = story->data;
+
+    while ((start = strstr(start, replace))) {
+        if (!dstr_space(story, insert_l - replace_l))
+            if (!dstr_grow(story)) err("Failed to allocate memory");
+
+        if (insert_l != replace_l) {
+            memmove(start + insert_l, start + replace_l, story->length -
+                    (start + replace_l - story->data));
+
+            /* Remember to null terminate the data so we can utilize it
+             * as we normally would */
+            story->length += insert_l - replace_l;
+            story->data[story->length] = 0;
+        }
+
+        memmove(start, insert, insert_l);
+    }
+}
+
+void madlibs(dstr *story)
+{
+    static const size_t buffer_size = 128;
+    char insert[buffer_size];
+    char replace[buffer_size];
+
+    char *start,
+         *end = story->data;
+
+    while (start = strchr(end, '<')) {
+        if (!(end = strchr(start, '>'))) err("Malformed brackets in input");
+
+        /* One extra for current char and another for nul byte */
+        strncpy(replace, start, end - start + 1);
+        replace[end - start + 1] = '\0';
+
+        printf("Enter value for field %s: ", replace);
+
+        fgets(insert, buffer_size, stdin);
+        const size_t il = strlen(insert) - 1;
+        if (insert[il] == '\n')
+            insert[il] = '\0';
+
+        dstr_replace_all(story, replace, insert);
+    }
+    printf("\n");
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc < 2) return 0;
+
+    FILE *fd = fopen(argv[1], "r");
+    if (!fd) err("Could not open file: '%s\n", argv[1]);
+
+    dstr *story = readinput(fd); fclose(fd);
+    if (!story) err("Failed to allocate memory");
+
+    madlibs(story);
+    printf("%s\n", story->data);
+    dstr_delete(story);
+    return 0;
+}