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Adds pattern matching to GDScript #6845

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merged 3 commits into from
Jan 14, 2017
Merged

Adds pattern matching to GDScript #6845

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f8a7c46
pattern matching: implemented parser
karroffel Sep 30, 2016
d445f06
pattern matcher: Implemented transformations
karroffel Oct 5, 2016
e781a7e
pattern matcher: Implemented backend
karroffel Oct 16, 2016
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67 changes: 66 additions & 1 deletion modules/gdscript/gd_compiler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1019,7 +1019,72 @@ Error GDCompiler::_parse_block(CodeGen& codegen,const GDParser::BlockNode *p_blo

switch(cf->cf_type) {


case GDParser::ControlFlowNode::CF_MATCH: {
GDParser::MatchNode *match = cf->match;

GDParser::IdentifierNode *id = memnew(GDParser::IdentifierNode);
id->name = "#match_value";

// var #match_value
// copied because there is no _parse_statement :(
codegen.add_stack_identifier(id->name, p_stack_level++);
codegen.alloc_stack(p_stack_level);
new_identifiers++;

GDParser::OperatorNode *op = memnew(GDParser::OperatorNode);
op->op=GDParser::OperatorNode::OP_ASSIGN;
op->arguments.push_back(id);
op->arguments.push_back(match->val_to_match);

int ret = _parse_expression(codegen, op, p_stack_level);
if (ret < 0) {
return ERR_PARSE_ERROR;
}

// break address
codegen.opcodes.push_back(GDFunction::OPCODE_JUMP);
codegen.opcodes.push_back(codegen.opcodes.size() + 3);
int break_addr = codegen.opcodes.size();
codegen.opcodes.push_back(GDFunction::OPCODE_JUMP);
codegen.opcodes.push_back(0); // break addr

for (int j = 0; j < match->compiled_pattern_branches.size(); j++) {
GDParser::MatchNode::CompiledPatternBranch branch = match->compiled_pattern_branches[j];

// jump over continue
// jump unconditionally
// continue address
// compile the condition
int ret = _parse_expression(codegen, branch.compiled_pattern, p_stack_level);
if (ret < 0) {
return ERR_PARSE_ERROR;
}

codegen.opcodes.push_back(GDFunction::OPCODE_JUMP_IF);
codegen.opcodes.push_back(ret);
codegen.opcodes.push_back(codegen.opcodes.size() + 3);
int continue_addr = codegen.opcodes.size();
codegen.opcodes.push_back(GDFunction::OPCODE_JUMP);
codegen.opcodes.push_back(0);



Error err = _parse_block(codegen, branch.body, p_stack_level, p_break_addr, continue_addr);
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If p_break_addr is changed to break_addr then break will work inside of a pattern branch. So no big changes needed to support that. However I think it would be a bad idea to do that since it will cause a lot of confusion amongst newbies and may lead people the wrong way.

break isn't match-idiomatic, so I think it would be a mistake to implement it that way.

if (err) {
return ERR_PARSE_ERROR;
}

codegen.opcodes.push_back(GDFunction::OPCODE_JUMP);
codegen.opcodes.push_back(break_addr);

codegen.opcodes[continue_addr + 1] = codegen.opcodes.size();
}

codegen.opcodes[break_addr + 1] = codegen.opcodes.size();


} break;

case GDParser::ControlFlowNode::CF_IF: {

#ifdef DEBUG_ENABLED
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