public override void DoVisit(AST_Block node)
{
Console.Write("(BLK ");
Console.Write(node.type + " {");
VisitChildren(node);
Console.Write("})");
}
//NOTE: returns jump instruction to be patched later
Instruction EmitConditionPlaceholderAndBody(AST_Block ast, int idx)
{
//condition
Visit(ast.children[idx]);
var jump_op = Emit(Opcodes.JumpZ, new int[] { 0 });
Visit(ast.children[idx + 1]);
return(jump_op);
}
void PatchBreaks(AST_Block block)
{
for (int i = non_patched_breaks.Count; i-- > 0;)
{
var npb = non_patched_breaks[i];
if (npb.block == block)
{
AddOffsetFromTo(npb.jump_op, Peek());
non_patched_breaks.RemoveAt(i);
}
}
}
void PatchContinues(AST_Block block)
{
for (int i = non_patched_continues.Count; i-- > 0;)
{
var npc = non_patched_continues[i];
if (npc.block == block)
{
AddOffsetFromTo(npc.jump_op, continue_jump_markers[npc.block]);
non_patched_continues.RemoveAt(i);
}
}
continue_jump_markers.Clear();
}
void VisitDefer(AST_Block ast)
{
var parent_block = ctrl_blocks.Count > 0 ? ctrl_blocks.Peek() : null;
if (parent_block != null)
{
block_has_defers.Add(parent_block);
}
var block_op = Emit(Opcodes.Block, new int[] { (int)ast.type, 0 /*patched later*/ });
VisitChildren(ast);
AddOffsetFromTo(block_op, Peek(), operand_idx: 1);
}
void VisitControlBlock(AST_Block ast)
{
var parent_block = ctrl_blocks.Count > 0 ? ctrl_blocks.Peek() : null;
bool parent_is_paral =
parent_block != null &&
(parent_block.type == BlockType.PARAL ||
parent_block.type == BlockType.PARAL_ALL);
bool is_paral =
ast.type == BlockType.PARAL ||
ast.type == BlockType.PARAL_ALL;
ctrl_blocks.Push(ast);
var block_op = Emit(Opcodes.Block, new int[] { (int)ast.type, 0 /*patched later*/ });
for (int i = 0; i < ast.children.Count; ++i)
{
var child = ast.children[i];
//NOTE: let's automatically wrap all children with sequence if
// they are inside paral block
if (is_paral &&
(!(child is AST_Block child_block) ||
(child_block.type != BlockType.SEQ && child_block.type != BlockType.DEFER)))
{
var seq_child = new AST_Block(BlockType.SEQ);
seq_child.children.Add(child);
child = seq_child;
}
Visit(child);
}
ctrl_blocks.Pop();
bool need_block = is_paral || parent_is_paral || block_has_defers.Contains(ast) || HasOffsetsTo(block_op);
if (need_block)
{
AddOffsetFromTo(block_op, Peek(), operand_idx: 1);
}
else
{
head.Remove(block_op);
}
}
public override void DoVisit(AST_Block ast)
{
switch (ast.type)
{
case BlockType.IF:
//if()
// ^-- to be patched with position out of 'if body'
//{
// ...
// jmp_opcode
// ^-- to be patched with position out of 'if body'
//}
//else if()
// ^-- to be patched with position out of 'if body'
//{
// ...
// jmp_opcode
// ^-- to be patched with position out of 'if body'
//}
//else
//{
//}
Instruction last_jmp_op = null;
int i = 0;
//NOTE: amount of children is even if there's no 'else'
for (; i < ast.children.Count; i += 2)
{
//break if there's only 'else leftover' left
if ((i + 2) > ast.children.Count)
{
break;
}
var if_op = EmitConditionPlaceholderAndBody(ast, i);
if (last_jmp_op != null)
{
AddOffsetFromTo(last_jmp_op, Peek());
}
//check if uncoditional jump out of 'if body' is required,
//it's required only if there are other 'else if' or 'else'
if (ast.children.Count > 2)
{
last_jmp_op = Emit(Opcodes.Jump, new int[] { 0 });
AddOffsetFromTo(if_op, Peek());
}
else
{
AddOffsetFromTo(if_op, Peek());
}
}
//check fo 'else leftover'
if (i != ast.children.Count)
{
Visit(ast.children[i]);
AddOffsetFromTo(last_jmp_op, Peek());
}
break;
case BlockType.WHILE:
{
if (ast.children.Count != 2)
{
throw new Exception("Unexpected amount of children (must be 2)");
}
loop_blocks.Push(ast);
var begin_op = Peek();
var cond_op = EmitConditionPlaceholderAndBody(ast, 0);
//to the beginning of the loop
var jump_op = Emit(Opcodes.Jump, new int[] { 0 });
AddOffsetFromTo(jump_op, begin_op);
//patch 'jump out of the loop' position
AddOffsetFromTo(cond_op, Peek());
PatchContinues(ast);
PatchBreaks(ast);
loop_blocks.Pop();
}
break;
case BlockType.DOWHILE:
{
if (ast.children.Count != 2)
{
throw new Exception("Unexpected amount of children (must be 2)");
}
loop_blocks.Push(ast);
var begin_op = Peek();
Visit(ast.children[0]);
Visit(ast.children[1]);
var cond_op = Emit(Opcodes.JumpZ, new int[] { 0 });
//to the beginning of the loop
var jump_op = Emit(Opcodes.Jump, new int[] { 0 });
AddOffsetFromTo(jump_op, begin_op);
//patch 'jump out of the loop' position
AddOffsetFromTo(cond_op, Peek());
PatchContinues(ast);
PatchBreaks(ast);
loop_blocks.Pop();
}
break;
case BlockType.FUNC:
{
VisitChildren(ast);
}
break;
case BlockType.SEQ:
case BlockType.PARAL:
case BlockType.PARAL_ALL:
{
VisitControlBlock(ast);
}
break;
case BlockType.DEFER:
{
VisitDefer(ast);
}
break;
default:
throw new Exception("Not supported block type: " + ast.type);
}
}
public abstract void DoVisit(AST_Block ast);
