From 48453f59ec93d9b8f70a17d3034e5ca3e4780ecd Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 26 May 2019 00:58:17 +0300
Subject: [PATCH] Support while loops in GLSL

Loops with only a condition expression present are now emitted as while
loops, even if they were originally for loops.
---
 source/programcompiler.cpp | 33 +++++++++++++++++++++------------
 source/programparser.cpp   | 19 +++++++++++++++++--
 source/programparser.h     |  3 ++-
 3 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/source/programcompiler.cpp b/source/programcompiler.cpp
index fd9c50db..afb2a3c3 100644
--- a/source/programcompiler.cpp
+++ b/source/programcompiler.cpp
@@ -543,23 +543,32 @@ void ProgramCompiler::Formatter::visit(Conditional &cond)
 
 void ProgramCompiler::Formatter::visit(Iteration &iter)
 {
-	formatted += "for(";
-	if(iter.init_statement)
-		iter.init_statement->visit(*this);
-	else
-		formatted += ';';
-	if(iter.condition)
+	if(!iter.init_statement && iter.condition && !iter.loop_expression)
 	{
-		formatted += ' ';
+		formatted += "while(";
 		iter.condition->visit(*this);
+		formatted += ')';
 	}
-	formatted += ';';
-	if(iter.loop_expression)
+	else
 	{
-		formatted += ' ';
-		iter.loop_expression->visit(*this);
+		formatted += "for(";
+		if(iter.init_statement)
+			iter.init_statement->visit(*this);
+		else
+			formatted += ';';
+		if(iter.condition)
+		{
+			formatted += ' ';
+			iter.condition->visit(*this);
+		}
+		formatted += ';';
+		if(iter.loop_expression)
+		{
+			formatted += ' ';
+			iter.loop_expression->visit(*this);
+		}
+		formatted += ')';
 	}
-	formatted += ')';
 
 	if(iter.body.body.empty())
 		formatted += " { }";
diff --git a/source/programparser.cpp b/source/programparser.cpp
index b607e1cf..c02adb32 100644
--- a/source/programparser.cpp
+++ b/source/programparser.cpp
@@ -484,7 +484,9 @@ RefPtr<Node> ProgramParser::parse_statement()
 	if(token=="if")
 		return parse_conditional();
 	else if(token=="for")
-		return parse_iteration();
+		return parse_for();
+	else if(token=="while")
+		return parse_while();
 	else if(token=="passthrough")
 		return parse_passthrough();
 	else if(token=="return")
@@ -843,7 +845,7 @@ RefPtr<Conditional> ProgramParser::parse_conditional()
 	return cond;
 }
 
-RefPtr<Iteration> ProgramParser::parse_iteration()
+RefPtr<Iteration> ProgramParser::parse_for()
 {
 	expect("for");
 	expect("(");
@@ -873,6 +875,19 @@ RefPtr<Iteration> ProgramParser::parse_iteration()
 	return loop;
 }
 
+RefPtr<Iteration> ProgramParser::parse_while()
+{
+	expect("while");
+	expect("(");
+	RefPtr<Iteration> loop = new Iteration;
+	loop->condition = parse_expression();
+	expect(")");
+
+	parse_block(loop->body, false);
+
+	return loop;
+}
+
 RefPtr<Passthrough> ProgramParser::parse_passthrough()
 {
 	expect("passthrough");
diff --git a/source/programparser.h b/source/programparser.h
index 903e5834..70781540 100644
--- a/source/programparser.h
+++ b/source/programparser.h
@@ -104,7 +104,8 @@ private:
 	RefPtr<ProgramSyntax::FunctionDeclaration> parse_function_declaration();
 	RefPtr<ProgramSyntax::InterfaceBlock> parse_interface_block();
 	RefPtr<ProgramSyntax::Conditional> parse_conditional();
-	RefPtr<ProgramSyntax::Iteration> parse_iteration();
+	RefPtr<ProgramSyntax::Iteration> parse_for();
+	RefPtr<ProgramSyntax::Iteration> parse_while();
 	RefPtr<ProgramSyntax::Passthrough> parse_passthrough();
 	RefPtr<ProgramSyntax::Return> parse_return();
 };
-- 
2.45.2