1 files changed, 85 insertions, 0 deletions
diff --git a/src/compiler/error_helper/error_helper.c b/src/compiler/error_helper/error_helper.c
new file mode 100644
index 0000000..fd648e4
--- /dev/null
+++ b/src/compiler/error_helper/error_helper.c
@@ -0,0 +1,85 @@
+#include "error_helper.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void printError(char const *error, SourceCode code, char const *begin,
+                char const *end, ...) {
+  va_list args;
+  va_start(args, end);
+  char *errorStr;
+  vasprintf(&errorStr, error, args);
+
+  char const *lineBegin = code;
+  int line = 1;
+
+  char const *iter = code;
+  for (; iter < begin; ++iter) {
+    const char c = *iter;
+    switch (c) {
+      case '\0':
+        fprintf(stderr,
+                "Compiler Internal Error: in printing errors at compiler %s:%d",
+                __FILE_NAME__, __LINE__);
+        exit(1);
+      case '\n':
+        lineBegin = iter + 1;
+        ++line;
+        break;
+    }
+  }
+  char const *lineEnd = end;
+
+  for (;; ++iter) {
+    const char c = *iter;
+    switch (c) {
+      case '\0':
+        if (iter < end) {
+          fprintf(
+              stderr,
+              "Compiler Internal Error: in printing errors at compiler %s:%d",
+              __FILE_NAME__, __LINE__);
+          exit(1);
+        }
+        lineEnd = iter;
+        goto AFTER_LOOP;
+      case '\n':
+        lineEnd = iter;
+        if (iter >= end) {
+          goto AFTER_LOOP;
+        }
+        break;
+    }
+  }
+AFTER_LOOP:
+
+  fprintf(stderr, "Error: %s at line %d\n", errorStr, line);
+
+  int printed = 0;
+  for (iter = lineBegin; iter < lineEnd; ++iter) {
+    fprintf(stderr, "%c", *iter);
+    if (*iter == '\n') {
+    PRINT_LINE:
+      for (int i = 0; i < printed; ++i) {
+        const char *ch = iter - printed + i;
+        if (begin <= ch && ch < end) {
+          fprintf(stderr, "^");
+        } else {
+          fprintf(stderr, " ");
+        }
+      }
+      if (iter + 1 != lineEnd) {
+        fprintf(stderr, "\n");
+        printed = 0;
+      }
+    } else if (iter + 1 == lineEnd) {
+      fprintf(stderr, "\n");
+      goto PRINT_LINE;
+    } else {
+      ++printed;
+    }
+  }
+  fprintf(stderr, "\n");
+  free(errorStr);
+}