Add while loop compilation

1 files changed, 34 insertions, 0 deletions

diff --git a/src/compiler.c b/src/compiler.c
index 0f9607e..ea9234a 100644
--- a/src/compiler.c
+++ b/src/compiler.c
@@ -559,8 +559,42 @@ compile_if(Chunk *chunk, Node *node) {
 }
 
 CompResult
+compile_while(Chunk *chunk, Node *node) {
+    sz start = array_size(chunk->code);
+    CompResult cond = compile_expr(chunk, node->while_cond);
+    OpCode jmpop;
+    switch (cond.type) {
+        case COMP_CONST: {
+            jmpop = OP_JMPFI;
+        } break;
+        case COMP_REG: {
+            jmpop = OP_JMPF;
+        } break;
+        default: {
+            return (CompResult){.type = COMP_ERR};
+        } break;
+    }
+    sz jump_a = array_size(chunk->code);
+
+    // Jump to the `end of the loop` branch.
+    EMIT_OP(jmpop, cond.idx, 0xff, 0, node->while_cond, chunk);
+
+    // Condition is true.
+    CompResult then_expr = compile_expr(chunk, node->while_expr);
+    sz end_expr = array_size(chunk->code);
+    sz loopback = add_constant(chunk, (start - end_expr));
+    EMIT_OP(OP_JMPI, loopback, 0, 0, node, chunk);
+    sz const_a = add_constant(chunk, end_expr - jump_a + 1);
+    chunk->code[jump_a].a = const_a;
+
+    // Return.
+    return (CompResult){.type = COMP_NIL};
+}
+
+CompResult
 compile_expr(Chunk *chunk, Node *node) {
     switch (node->kind) {
+        case NODE_WHILE: return compile_while(chunk, node);
         case NODE_IF: return compile_if(chunk, node);
         // Logic.
         // case NODE_XOR: