Make text indexing optional

4 files changed, 25 insertions, 5 deletions

diff --git a/src/compile/indexing.c b/src/compile/indexing.c
index cca06184..9d3501c9 100644
--- a/src/compile/indexing.c
+++ b/src/compile/indexing.c
@@ -73,8 +73,15 @@ Text_t compile_indexing(env_t *env, ast_t *ast, bool checked) {
                          compile_none(table_type->value_type), ", ", compile_type_info(container_t), ")");
         }
     } else if (container_t->tag == TextType) {
-        return Texts("Text$cluster(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
-                     compile_to_type(env, indexing->index, Type(BigIntType)), ")");
+        if (checked) {
+            int64_t start = (int64_t)(ast->start - ast->file->text), end = (int64_t)(ast->end - ast->file->text);
+            return Texts("Text$cluster_checked(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
+                         compile_to_type(env, indexing->index, Type(BigIntType)), ", ", String(start), ", ",
+                         String(end), ")");
+        } else {
+            return Texts("Text$cluster(", compile_to_pointer_depth(env, indexing->indexed, 0, false), ", ",
+                         compile_to_type(env, indexing->index, Type(BigIntType)), ")");
+        }
     } else {
         code_err(ast, "Indexing is not supported for type: ", type_to_str(container_t));
     }
diff --git a/src/stdlib/text.c b/src/stdlib/text.c
index ed4023a4..f4533be5 100644
--- a/src/stdlib/text.c
+++ b/src/stdlib/text.c
@@ -725,7 +725,10 @@ Text_t Text$reversed(Text_t text) {
 }
 
 public
-PUREFUNC Text_t Text$cluster(Text_t text, Int_t index) { return Text$slice(text, index, index); }
+PUREFUNC OptionalText_t Text$cluster(Text_t text, Int_t index) {
+    Text_t slice = Text$slice(text, index, index);
+    return slice.length <= 0 ? NONE_TEXT : slice;
+}
 
 static Text_t Text$from_components(List_t graphemes, Table_t unique_clusters) {
     size_t blob_size = (sizeof(int32_t[unique_clusters.entries.length]) + sizeof(uint8_t[graphemes.length]));
diff --git a/src/stdlib/text.h b/src/stdlib/text.h
index 5fa95675..c08e5267 100644
--- a/src/stdlib/text.h
+++ b/src/stdlib/text.h
@@ -41,7 +41,17 @@ Text_t Text$slice(Text_t text, Int_t first_int, Int_t last_int);
 Text_t Text$from(Text_t text, Int_t first);
 Text_t Text$to(Text_t text, Int_t last);
 Text_t Text$reversed(Text_t text);
-Text_t Text$cluster(Text_t text, Int_t index_int);
+OptionalText_t Text$cluster(Text_t text, Int_t index_int);
+#define Text$cluster_checked(text_expr, index_expr, start, end)                                                        \
+    ({                                                                                                                 \
+        const Text_t text = text_expr;                                                                                 \
+        Int_t index = index_expr;                                                                                      \
+        OptionalText_t cluster = Text$cluster(text, index);                                                            \
+        if (unlikely(cluster.length < 0))                                                                              \
+            fail_source(__SOURCE_FILE__, start, end, "Invalid text index: ", index, " (text has length ",              \
+                        (int64_t)text.length, ")\n");                                                                  \
+        cluster;                                                                                                       \
+    })
 OptionalText_t Text$from_str(const char *str);
 OptionalText_t Text$from_strn(const char *str, size_t len);
 PUREFUNC uint64_t Text$hash(const void *text, const TypeInfo_t *);
diff --git a/src/typecheck.c b/src/typecheck.c
index eba12a6e..2af2408e 100644
--- a/src/typecheck.c
+++ b/src/typecheck.c
@@ -897,7 +897,7 @@ type_t *get_type(env_t *env, ast_t *ast) {
             if (table_type->default_value) return table_type->value_type;
             return Type(OptionalType, table_type->value_type);
         } else if (value_t->tag == TextType) {
-            return value_t;
+            return Type(OptionalType, value_t);
         } else {
             code_err(ast, "I don't know how to index ", type_to_str(indexed_t), " values");
         }