Initial commit of template engine code (not hooked up yet)

1 files changed, 190 insertions, 0 deletions

diff --git a/src/template.c b/src/template.c
new file mode 100644
index 0000000..335da85
--- /dev/null
+++ b/src/template.c
@@ -0,0 +1,190 @@
+//
+// Created by jhunk on 12/17/23.
+//
+
+#include "template.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+
+struct tpl_item {
+    char *key;
+    char *ptr;
+};
+struct tpl_item *tpl_pool[1024] = {0};
+unsigned tpl_pool_used = 0;
+
+void tpl_register(char *key, char *ptr) {
+    struct tpl_item *item = NULL;
+    item = calloc(1, sizeof(*item));
+    if (!item) {
+        perror("unable to register tpl_item");
+        exit(1);
+    }
+    item->key = strdup(key);
+    item->ptr = ptr;
+    tpl_pool[tpl_pool_used] = item;
+    tpl_pool_used++;
+}
+
+void tpl_free() {
+    for (unsigned i = 0; i < tpl_pool_used; i++) {
+        struct tpl_item *item = tpl_pool[i];
+        if (item) {
+            if (item->key) {
+                free(item->key);
+            }
+            free(item);
+        }
+    }
+}
+
+char *tpl_getval(char *key) {
+    char *result = NULL;
+    for (size_t i = 0; i < tpl_pool_used; i++) {
+        if (tpl_pool[i]->key) {
+            if (!strcmp(tpl_pool[i]->key, key)) {
+                result = tpl_pool[i]->ptr;
+                break;
+            }
+        }
+    }
+    return result;
+}
+
+static int grow(size_t z, size_t *output_bytes, char **output) {
+    if (z > *output_bytes) {
+        size_t new_size = *output_bytes + z + 1;
+#ifdef DEBUG
+        fprintf(stderr, "template output buffer new size: %zu\n", *output_bytes);
+#endif
+        char *tmp = realloc(*output, new_size);
+        if (!*tmp) {
+            perror("realloc failed");
+            return -1;
+        }
+        memset(tmp + strlen(tmp), 0, new_size - strlen(tmp));
+        *output = tmp;
+        *output_bytes = new_size;
+    }
+    return 0;
+}
+
+char *tpl_render(char *str) {
+    if (!str) {
+        return NULL;
+    }
+    size_t output_bytes = strlen(str);
+    char *output;
+    char *b_close, *pos;
+    pos = str;
+
+    output = calloc(output_bytes + 1, sizeof(*output));
+    if (!output) {
+        perror("unable to allocate output buffer");
+        return NULL;
+    }
+
+    size_t z = 0;
+    while (*pos != 0) {
+        char key[255] = {0};
+        char *value = NULL;
+
+        grow(z, &output_bytes, &output);
+        // At opening brace
+        if (!strncmp(pos, "{{", 2)) {
+            // Scan until key is reached
+            while (!isalnum(*pos)) {
+                pos++;
+            }
+
+            // Read key name
+            size_t key_len = 0;
+            while (isalnum(*pos) || *pos != '}') {
+                key[key_len] = *pos;
+                key_len++;
+                pos++;
+            }
+
+            char *type_stop = NULL;
+            type_stop = strchr(key, ':');
+
+            int do_env = 0;
+            if (type_stop) {
+                if (!strncmp(key, "env", type_stop - key)) {
+                    do_env = 1;
+                }
+            }
+
+            // Find closing brace
+            b_close = strstr(pos, "}}");
+            if (!b_close) {
+                grow(z + strlen(pos), &output_bytes, &output);
+                strcpy(output, pos);
+                z += strlen(pos);
+                continue;
+            }
+            // Jump past closing brace
+            pos = b_close + 2;
+
+            if (do_env) {
+                char *k = type_stop + 1;
+                size_t klen = strlen(k);
+                memmove(key, k, klen);
+                key[klen] = 0;
+                char *env_val = getenv(key);
+                value = strdup(env_val ? env_val : "");
+            } else {
+                // Read replacement value
+                value = tpl_getval(key);
+            }
+        }
+
+        if (value) {
+            // Append replacement value
+            grow(z + strlen(value), &output_bytes, &output);
+            strcat(output, value);
+            // Set output iterator to end of replacement value
+            z += strlen(value);
+        }
+
+#ifdef DEBUG
+        fprintf(stderr, "z=%zu, output_bytes=%zu\n", z, output_bytes);
+#endif
+        output[z] = *pos;
+        pos++;
+        z++;
+    }
+#ifdef DEBUG
+    fprintf(stderr, "template output length: %zu\n", strlen(output));
+    fprintf(stderr, "template output bytes: %zu\n", output_bytes);
+#endif
+    return output;
+}
+
+/*
+const char *TESTDATA = "follow the {{ env:PATH }}\ni have a {{ COLOR}} pencil box\n\nthe cup is full of {{LIQUID }}\n{{GOAT}}, the barn is {{  COLOR  }} too!\n";
+int main() {
+    char *name = "couch";
+    char *liquid = "milk";
+    char *color = "brown";
+    char *meh = "MEHHHHHHHH";
+
+    tpl_register("THING", name);
+    tpl_register("LIQUID", liquid);
+    tpl_register("COLOR", color);
+    tpl_register("GOAT", meh);
+
+    puts(TESTDATA);
+    puts("----------\n");
+
+    char *output = tpl_render(TESTDATA, strlen(TESTDATA) + 1024);
+    printf("%s\n", output);
+    free(output);
+    tpl_free();
+    return 0;
+}
+ */