Introduce Parser and Expression hierarchy.

1 files changed, 182 insertions, 0 deletions

diff --git a/JSImpl/src/Parser.cpp b/JSImpl/src/Parser.cpp
new file mode 100644
index 0000000..1eceb7f
--- /dev/null
+++ b/JSImpl/src/Parser.cpp
@@ -0,0 +1,182 @@
+#include "Parser.h"
+
+class Parser
+{
+public:
+	Parser(IPLVector<Token>& tokens, const std::function<void()>& onError = {});
+	ExpressionPtr Parse();
+private:
+	bool MatchOneOf(IPLVector<TokenType> types);
+	bool Match(TokenType type);
+	ExpressionPtr Unary();
+	ExpressionPtr LeftSideExpression();
+	ExpressionPtr SimpleExpression();
+
+	Token& Prev() { return m_Tokens[m_Current - 1]; }
+	std::function<void()> OnError;
+	unsigned m_Current;
+	IPLVector<Token> m_Tokens;
+};
+
+Parser::Parser(IPLVector<Token>& tokens, const std::function<void()>& onError)
+	: m_Tokens(tokens)
+	, OnError(onError)
+	, m_Current(0)
+{
+}
+
+bool Parser::MatchOneOf(IPLVector<TokenType> types)
+{
+	for (auto t : types)
+	{
+		if (t == m_Tokens[m_Current].Type)
+		{
+			++m_Current;
+			return true;
+		}
+	}
+	return false;
+}
+
+bool Parser::Match(TokenType type)
+{
+	if (type == m_Tokens[m_Current].Type)
+	{
+		++m_Current;
+		return true;
+	}
+	return false;
+}
+
+ExpressionPtr Parser::SimpleExpression()
+{
+	//SimpleExpression
+	//	this
+	//	| null
+	//	| true
+	//	| false
+	//	| Number
+	//	| String
+	//	| Identifier
+	//	| RegularExpression
+	//	| ParenthesizedExpression
+	//	| ArrayLiteral
+	if (Match({TokenType::Number}))
+	{
+		return IPLMakeSharePtr<LiteralExpression>(Prev().Number);
+	}
+	else if (Match({ TokenType::String }))
+	{
+		return IPLMakeSharePtr<LiteralExpression>(Prev().Lexeme);
+	}
+	else
+	{
+		// TODO implement
+		return ExpressionPtr();
+	}
+}
+
+ExpressionPtr Parser::LeftSideExpression()
+{
+	//LeftSideExpression ->
+	//	CallExpression
+	//	| ShortNewExpression
+
+	//	CallExpression ->
+	//	PrimaryExpression
+	//	| FullNewExpression
+	//	| CallExpression MemberOperator
+	//	| CallExpression Arguments
+
+	//	FullNewExpression -> new FullNewSubexpression Arguments
+
+	//	ShortNewExpression -> new ShortNewSubexpression
+
+	//	FullNewSubexpression ->
+	//	PrimaryExpressionnormal
+	//	| FullNewExpression
+	//	| FullNewSubexpression MemberOperator
+
+	//	ShortNewSubexpression ->
+	//	FullNewSubexpression
+	//	| ShortNewExpression
+
+	//	MemberOperator ->
+	//	[Expressionnormal, allowIn]
+	//| .Identifier
+
+	//	Arguments ->
+	//	()
+	//	| (ArgumentList)
+
+	//	ArgumentList ->
+	//	AssignmentExpressionnormal, allowIn
+	//	| ArgumentList, AssignmentExpressionnormal, allowIn
+	return SimpleExpression();
+}
+
+ExpressionPtr Parser::Unary()
+{
+
+	//UnaryExpression
+	//	PostfixExpression
+	//	| delete LeftSideExpressionnormal
+	//	| ++LeftSideExpressionnormal
+	//	| --LeftSideExpressionnormal
+	//	| void UnaryExpressionnormal
+	//	| typeof UnaryExpressionnormal
+	//	| +UnaryExpressionnormal
+	//	| -UnaryExpressionnormal
+	//	| ~UnaryExpressionnormal
+	//	| !UnaryExpressionnormal
+	if (MatchOneOf({ 
+		TokenType::Delete,
+		TokenType::MinusMinus,
+		TokenType::PlusPlus,
+		}))
+	{
+		auto ls = LeftSideExpression();
+		auto suffix = false;
+		return IPLMakeSharePtr<UnaryExpression>(ls, Prev().Type, suffix);
+	}
+	else if (MatchOneOf({
+		TokenType::Void,
+		TokenType::Typeof,
+		TokenType::Plus,
+		TokenType::Minus,
+		TokenType::BitwiseNot,
+		TokenType::Bang,
+	}))
+	{
+		auto ls = Unary();
+		auto suffix = false;
+		return IPLMakeSharePtr<UnaryExpression>(ls, Prev().Type, suffix);
+	}
+	else
+	{
+		//PostfixExpression
+		//	LeftSideExpression
+		//	| LeftSideExpression++
+		//	| LeftSideExpression--
+		auto leftSide = LeftSideExpression();
+		if (MatchOneOf({ TokenType::PlusPlus, TokenType::MinusMinus }))
+		{
+			auto suffix = true;
+			return IPLMakeSharePtr<UnaryExpression>(leftSide, Prev().Type, suffix);
+		}
+		return leftSide;
+	}
+}
+
+ExpressionPtr Parser::Parse()
+{
+	// TODO implement full grammar
+	return Unary();
+}
+
+
+ExpressionPtr Parse(IPLVector<Token>& tokens, const std::function<void()>& onError)
+{
+	Parser p(tokens, onError);
+	return p.Parse();
+}
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