While loops.

.gitignore

@@ -6,6 +6,7 @@ out/
 src/*.o
 tmp/
 .aiignore
+dev.txt
 fun
 fun_test
 test_opcodes

examples/while_test.fun

@@ -0,0 +1,35 @@
+#!/usr/bin/env fun
+
+// While loops feature test: simple loops, nested with if/else, and functions
+
+print("=== while test start ===")
+
+// Simple counter 0..4
+number i = 0
+while (i < 5)
+  print(i)        // expect 0,1,2,3,4
+  i = i + 1
+
+// Nested while with if/else
+number a = 3
+while (a > 0)
+  if (a == 2)
+    print(99)     // special case when a == 2
+  else
+    print(a)
+  a = a - 1       // expect: 3, 99, 1
+
+// While with false condition: body should not run
+while (0)
+  print(123)
+
+// Function using while
+fun countdown(n)
+  while (n > 0)
+    print(n)
+    n = n - 1
+  return 0
+
+print(countdown(3)) // expect: 3,2,1 then 0
+
+print("=== while test end ===")

src/parser.c

@@ -380,6 +380,22 @@ static int emit_multiplicative(Bytecode *bc, const char *src, size_t len, size_t
     if (!emit_unary(bc, src, len, pos)) return 0;
     for (;;) {
         skip_spaces(src, len, pos);
+
+        /* Stop expression at start of inline comment */
+        if (*pos + 1 < len && src[*pos] == '/' && src[*pos + 1] == '/') {
+            break;
+        }
+        /* Skip block comments inside expressions */
+        if (*pos + 1 < len && src[*pos] == '/' && src[*pos + 1] == '*') {
+            size_t p = *pos + 2;
+            while (p + 1 < len && !(src[p] == '*' && src[p + 1] == '/')) {
+                p++;
+            }
+            if (p + 1 < len) p += 2; /* consume closing marker */
+            *pos = p;
+            continue;
+        }
+
         if (*pos < len && src[*pos] == '*') {
             (*pos)++;
             if (!emit_unary(bc, src, len, pos)) { parser_fail(*pos, "Expected expression after '*'"); return 0; }
@@ -684,13 +700,18 @@ static void parse_simple_statement(Bytecode *bc, const char *src, size_t len, si
         }
 
         /* assignment or simple call */
-        int gi = sym_index(name);
+        int lidx = local_find(name);
+        int gi = (lidx < 0) ? sym_index(name) : -1;
         free(name);
         skip_spaces(src, len, &local_pos);
         if (local_pos < len && src[local_pos] == '=') {
             local_pos++; /* '=' */
             if (emit_expression(bc, src, len, &local_pos)) {
-                bytecode_add_instruction(bc, OP_STORE_GLOBAL, gi);
+                if (lidx >= 0) {
+                    bytecode_add_instruction(bc, OP_STORE_LOCAL, lidx);
+                } else {
+                    bytecode_add_instruction(bc, OP_STORE_GLOBAL, gi);
+                }
             }
             *pos = local_pos;
             skip_to_eol(src, len, pos);
@@ -937,6 +958,41 @@ static void parse_block(Bytecode *bc, const char *src, size_t len, size_t *pos,
             continue;
         }
 
+        /* while loop */
+        if (starts_with(src, len, *pos, "while")) {
+            *pos += 5;
+            skip_spaces(src, len, pos);
+
+            int loop_start = bc->instr_count;
+
+            /* condition */
+            if (!emit_expression(bc, src, len, pos)) {
+                int ci = bytecode_add_constant(bc, make_int(0));
+                bytecode_add_instruction(bc, OP_LOAD_CONST, ci);
+            }
+            /* end of condition */
+            skip_to_eol(src, len, pos);
+
+            /* jump over body if false */
+            int jmp_false = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
+
+            /* parse body at increased indent (peek indent without advancing pos) */
+            int body_indent = 0;
+            size_t look_body = *pos;
+            if (read_line_start(src, len, &look_body, &body_indent) && body_indent > current_indent) {
+                parse_block(bc, src, len, pos, body_indent);
+            } else {
+                /* empty body allowed */
+            }
+
+            /* back edge to loop start */
+            bytecode_add_instruction(bc, OP_JUMP, loop_start);
+
+            /* patch false jump to here (after body) */
+            bytecode_set_operand(bc, jmp_false, bc->instr_count);
+            continue;
+        }
+
         /* otherwise: simple statement on this line */
         parse_simple_statement(bc, src, len, pos);
     }