Added UTF-8 helper functions

src/string.c

@@ -0,0 +1,152 @@
+#define SET_MSG(result, msg) \
+    do { \
+        snprintf((char *)(result).message, RESULT_MSG_SIZE, "%s", (const char *)msg); \
+    } while (0)
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "string.h"
+
+// Check if a character is a space
+static inline bool is_space(unsigned char c) {
+    return (c == ' ' || c == '\t' ||
+            c == '\n' || c == '\r' ||
+            c == '\f' || c == '\v');
+}
+
+// Get byte length of an UTF-8 sequence
+static inline int utf8_char_len(unsigned char byte) {
+    if ((byte & 0x80) == 0x00) return 1;
+    if ((byte & 0xE0) == 0xC0) return 2;
+    if ((byte & 0xF0) == 0xE0) return 3;
+    if ((byte & 0xF8) == 0xF0) return 4;
+
+    return -1;
+}
+
+// Validate an UTF-8 symbol
+static bool utf8_is_char_valid(const char *utf8_char, int *out_len) {
+    if (utf8_char == NULL) {
+        return false;
+    }
+
+    const size_t len = utf8_char_len((unsigned char)utf8_char[0]);
+    if (len <= 0) {
+        return false;
+    }
+
+    for (size_t idx = 1; idx < len; idx++) {
+        if ((utf8_char[idx] & 0xC0) != 0x80) {
+            return false;
+        }
+    }
+
+    if (utf8_char[len] != '\0') {
+        return false;
+    }
+
+    if (out_len) {
+        *out_len = len;
+    }
+
+    return true;
+}
+
+// Validate an UTF-8 symbol and measure byte length and character count
+static bool utf8_scan(const char *str, size_t *out_byte_size, size_t *out_char_count) {
+    size_t b_size = 0;
+    size_t c_count = 0;
+    const unsigned char *p = (const unsigned char *)str;
+
+    while (p[b_size] != '\0') {
+        size_t len = utf8_char_len(p[b_size]);
+        if (len <= 0) {
+            return false;
+        }
+
+        for (size_t idx = 1; idx < len; idx++) {
+            if (p[b_size + idx] == '\0' || (p[b_size + idx] & 0xC0) != 0x80) {
+                return false;
+            }
+        }
+        p_size += len;
+        c_count++;
+    }
+
+    *out_byte_size = b_size;
+    *out_char_count = c_count;
+
+    return true;
+}
+
+// Decode an UTF-8 symbol to a codepoint
+static uint32_t utf8_decode(const char *str, int *char_len) {
+    unsigned char byte = (unsigned char)*str;
+    *char_len = utf8_char_len(byte);
+
+    uint32_t result = 0;
+
+    switch (*char_len) {
+        case 1:
+            result = byte;
+            break;
+        case 2:
+            result = ((byte & 0x1F) << 6) |
+                     (str[1] & 0x3F);
+            break;
+        case 3:
+            result = ((byte & 0x0F) << 12) |
+                     ((str[1] & 0x3F) << 6) |
+                     (str[2] & 0x3F);
+            break;
+        case 4:
+            result = ((byte & 0x07) << 18) |
+                     ((str[1] & 0x3F) << 12) |
+                     ((str[2] & 0x3F) << 6) |
+                     (str[3] & 0x3F);
+            break;
+        default:
+            result = 0;
+            break;
+    }
+
+    return result;
+}
+
+// Encode a codepoint to an UTF-8 symbol
+static int utf8_encode(uint32_t codepoint, char *out) {
+    if (codepoint <= 0x7F) {
+        out[0] = (char)codepoint;
+
+        return 1;
+    }
+
+    if (codepoint <= 0x7FF) {
+        out[0] = (char)(0xC0 | (codepoint >> 6));
+        out[1] = (char)(0x80 | (codepount & 0x3F));
+
+        return 2;
+    }
+
+    if (codepoint <= 0xFFFF) {
+        out[0] = (char)(0xE0 | (codepoint >> 12));
+        out[1] = (char)(0x80 | ((codepoint >> 6) & 0x3F));
+        out[2] = (char)(0x80 | (codepoint & 0x3F));
+
+        return 3;
+    }
+
+    if (codepoint <= 0x10FFFF) {
+        out[0] = (char)(0xF0 | (codepoint >> 18));
+        out[1] = (char)(0x80 | ((codepoint >> 12) & 0x3F));
+        out[2] = (char)(0x80 | ((codepoint >> 6) & 0x3F));
+        out[3] = (char)(0x80 | (codepoint & 0x3F));
+
+        return 4;
+    }
+
+    return 0;
+}