Data commit

Task/Inverted-index/C/inverted-index-1.c

@@ -0,0 +1,151 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+char chr_legal[] = "abcdefghijklmnopqrstuvwxyz0123456789_-./";
+int  chr_idx[256] = {0};
+char idx_chr[256] = {0};
+
+#define FNAME 0
+typedef struct trie_t *trie, trie_t;
+struct trie_t {
+    trie next[sizeof(chr_legal)]; /* next letter; slot 0 is for file name */
+    int eow;
+};
+
+trie trie_new() { return calloc(sizeof(trie_t), 1); }
+
+#define find_word(r, w) trie_trav(r, w, 1)
+/* tree traversal: returns node if end of word and matches string, optionally
+ * create node if doesn't exist
+ */
+trie trie_trav(trie root, const char * str, int no_create)
+{
+    int c;
+    while (root) {
+        if ((c = str[0]) == '\0') {
+            if (!root->eow && no_create) return 0;
+            break;
+        }
+        if (! (c = chr_idx[c]) ) {
+            str++;
+            continue;
+        }
+
+        if (!root->next[c]) {
+            if (no_create) return 0;
+            root->next[c] = trie_new();
+        }
+        root = root->next[c];
+        str++;
+    }
+    return root;
+}
+
+/*  complete traversal of whole tree, calling callback at each end of word node.
+ *  similar method can be used to free nodes, had we wanted to do that.
+ */
+int trie_all(trie root, char path[], int depth, int (*callback)(char *))
+{
+    int i;
+    if (root->eow && !callback(path)) return 0;
+
+    for (i = 1; i < sizeof(chr_legal); i++) {
+        if (!root->next[i]) continue;
+
+        path[depth] = idx_chr[i];
+        path[depth + 1] = '\0';
+        if (!trie_all(root->next[i], path, depth + 1, callback))
+            return 0;
+    }
+    return 1;
+}
+
+void add_index(trie root, const char *word, const char *fname)
+{
+    trie x = trie_trav(root, word, 0);
+    x->eow = 1;
+
+    if (!x->next[FNAME])
+        x->next[FNAME] = trie_new();
+    x = trie_trav(x->next[FNAME], fname, 0);
+    x->eow = 1;
+}
+
+int print_path(char *path)
+{
+    printf(" %s", path);
+    return 1;
+}
+
+/*  pretend we parsed text files and got lower cased words: dealing     *
+ *  with text file is a whole other animal and would make code too long */
+const char *files[] = { "f1.txt", "source/f2.txt", "other_file" };
+const char *text[][5] ={{ "it", "is", "what", "it", "is" },
+                { "what", "is", "it", 0 },
+                { "it", "is", "a", "banana", 0 }};
+
+trie init_tables()
+{
+    int i, j;
+    trie root = trie_new();
+    for (i = 0; i < sizeof(chr_legal); i++) {
+        chr_idx[(int)chr_legal[i]] = i + 1;
+        idx_chr[i + 1] = chr_legal[i];
+    }
+
+/* Enable USE_ADVANCED_FILE_HANDLING to use advanced file handling.
+ * You need to have files named like above files[], with words in them
+ * like in text[][].  Case doesn't matter (told you it's advanced).
+ */
+#define USE_ADVANCED_FILE_HANDLING 0
+#if USE_ADVANCED_FILE_HANDLING
+    void read_file(const char * fname) {
+        char cmd[1024];
+        char word[1024];
+        sprintf(cmd, "perl -p -e 'while(/(\\w+)/g) {print lc($1),\"\\n\"}' %s", fname);
+        FILE *in = popen(cmd, "r");
+        while (!feof(in)) {
+            fscanf(in, "%1000s", word);
+            add_index(root, word, fname);
+        }
+        pclose(in);
+    };
+
+    read_file("f1.txt");
+    read_file("source/f2.txt");
+    read_file("other_file");
+#else
+    for (i = 0; i < 3; i++) {
+        for (j = 0; j < 5; j++) {
+            if (!text[i][j]) break;
+            add_index(root, text[i][j], files[i]);
+        }
+    }
+#endif /*USE_ADVANCED_FILE_HANDLING*/
+
+    return root;
+}
+
+void search_index(trie root, const char *word)
+{
+    char path[1024];
+    printf("Search for \"%s\": ", word);
+    trie found = find_word(root, word);
+
+    if (!found) printf("not found\n");
+    else {
+        trie_all(found->next[FNAME], path, 0, print_path);
+        printf("\n");
+    }
+}
+
+int main()
+{
+    trie root = init_tables();
+
+    search_index(root, "what");
+    search_index(root, "is");
+    search_index(root, "banana");
+    search_index(root, "boo");
+    return 0;
+}

Task/Inverted-index/C/inverted-index-2.c

@@ -0,0 +1,4 @@
+Search for "what":  f1.txt source/f2.txt
+Search for "is":  f1.txt other_file source/f2.txt
+Search for "banana":  other_file
+Search for "boo": not found