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Parser.cs
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199 lines (157 loc) · 3.55 KB
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using System;
using System.IO;
namespace ReClassNET.AddressParser
{
public class Parser
{
private readonly ITokenizer tokenizer;
public Parser(ITokenizer tokenizer)
{
this.tokenizer = tokenizer;
}
public IExpression ParseExpression()
{
var expr = ParseAddSubtract();
if (tokenizer.Token != Token.None)
{
throw new ParseException("Unexpected characters at end of expression");
}
return expr;
}
private IExpression ParseAddSubtract()
{
var lhs = ParseMultiplyDivide();
while (true)
{
if (tokenizer.Token == Token.Add || tokenizer.Token == Token.Subtract)
{
var token = tokenizer.Token;
tokenizer.ReadNextToken();
var rhs = ParseMultiplyDivide();
if (token == Token.Add)
{
lhs = new AddExpression(lhs, rhs);
}
else
{
lhs = new SubtractExpression(lhs, rhs);
}
}
else
{
return lhs;
}
}
}
private IExpression ParseMultiplyDivide()
{
var lhs = ParseUnary();
while (true)
{
if (tokenizer.Token == Token.Multiply || tokenizer.Token == Token.Divide)
{
var token = tokenizer.Token;
tokenizer.ReadNextToken();
var rhs = ParseUnary();
if (token == Token.Multiply)
{
lhs = new MultiplyExpression(lhs, rhs);
}
else
{
lhs = new DivideExpression(lhs, rhs);
}
}
else
{
return lhs;
}
}
}
private IExpression ParseUnary()
{
while (true)
{
if (tokenizer.Token == Token.Add)
{
tokenizer.ReadNextToken();
continue;
}
if (tokenizer.Token == Token.Subtract)
{
tokenizer.ReadNextToken();
var rhs = ParseUnary();
return new NegateExpression(rhs);
}
return ParseLeaf();
}
}
private IExpression ParseLeaf()
{
switch (tokenizer.Token)
{
case Token.Number:
{
var node = new ConstantExpression(tokenizer.Number);
tokenizer.ReadNextToken();
return node;
}
case Token.OpenParenthesis:
{
tokenizer.ReadNextToken();
var node = ParseAddSubtract();
if (tokenizer.Token != Token.CloseParenthesis)
{
throw new ParseException("Missing close parenthesis");
}
tokenizer.ReadNextToken();
return node;
}
case Token.OpenBrackets:
{
tokenizer.ReadNextToken();
var node = ParseAddSubtract();
var byteCount = IntPtr.Size;
if (tokenizer.Token == Token.Comma)
{
tokenizer.ReadNextToken();
if (tokenizer.Token != Token.Number)
{
throw new ParseException("Missing read byte count");
}
if (tokenizer.Number != 4 && tokenizer.Number != 8)
{
throw new ParseException("The byte count must be 4 or 8.");
}
byteCount = (int)tokenizer.Number;
tokenizer.ReadNextToken();
}
if (tokenizer.Token != Token.CloseBrackets)
{
throw new ParseException("Missing close bracket");
}
tokenizer.ReadNextToken();
return new ReadMemoryExpression(node, byteCount);
}
case Token.Identifier:
{
var node = new ModuleExpression(tokenizer.Identifier);
tokenizer.ReadNextToken();
return node;
}
default:
throw new ParseException($"Unexpect token: {tokenizer.Token}");
}
}
public static IExpression Parse(string str)
{
using var sr = new StringReader(str);
return Parse(new Tokenizer(sr));
}
private static IExpression Parse(ITokenizer tokenizer)
{
var parser = new Parser(tokenizer);
return parser.ParseExpression();
}
}
}