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Posted
over 9 years
ago
by
WiredWiz
The language I'm building a grammar for is generating a reduce-reduce conflict and I'm not sure how to read the conflict. I'm assuming in this case I should insert a ReduceHere() call somewhere in my grammar to clear up the conflict but I lack the
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understanding currently to know where this goes and exactly why (I assume it to be a conflict between potential expressions using , , -- and -). The conflict message is as follows:
State S53 (Inadequate)
Reduce-reduce conflicts on inputs: -- < || && ^ == != > <= >= << >> - * / % in
Reduce items:
Unary Expression -> Unary Operator Primary Expression · [ -- < || && ^ == != > <= >= << >> - * / % in Semicolon Comma }]
Expression -> Primary Expression · [ -- < || && ^ == != > <= >= << >> - * / % in]
Transitions:
My grammar includes operators common to C# such as , --, ==, !=, etc. as you can see. I used the example C# grammar in irony as a starting point. I actually ran into a number of conflicts initially, so I stripped the grammar down to a simplified version with the intention of slowly adding grammar parts back until I hit a conflict and then solving the conflict. I'm hoping by better understanding this conflict and the proper solution I can apply that knowledge to future conflicts and not nag folks with questions ;). In the current stripped down state the entire grammar is as follows:
using System;
using Irony.Parsing;
namespace Org.Edgerunner.MooSharp.Parser
{
[Language("Moo#", "1.0", "The Moo# programming language, an extended version of the original Moo language")]
public class MooSharpGrammar : Irony.Parsing.Grammar
{
/// <summary>
/// Initializes a new instance of the <see cref="MooSharpGrammar"/> class.
/// </summary>
public MooSharpGrammar()
: base(false)
{
#region declarations
StringLiteral stringLiteral = MooTerminalFactory.CreateMooString("StringLiteral");
Irony.Parsing.NumberLiteral number = MooTerminalFactory.CreateMooNumber("Number");
ObjectLiteral objectLiteral = new ObjectLiteral("Object");
ErrorTerminal error = new ErrorTerminal("ErrorCode", typeof(string));
IdentifierTerminal identifier = MooTerminalFactory.CreateMooIdentifier("Identifier");
KeyTerm lcbr = ToTerm("{");
KeyTerm rcbr = ToTerm("}");
KeyTerm comma = ToTerm(",", "Comma");
KeyTerm semi = ToTerm(";", "Semicolon");
KeyTerm at = ToTerm("@", "at");
CommentTerminal singleLineComment = new CommentTerminal("SingleLineComment", "//", "\r", "\n", "\u2085", "\u2028", "\u2029");
CommentTerminal delimitedComment = new CommentTerminal("DelimitedComment", "/*", "*/");
NonGrammarTerminals.Add(singleLineComment);
NonGrammarTerminals.Add(delimitedComment);
var literal = new NonTerminal("Literal");
var incrOrDecr = new NonTerminal("Incr Or Decr");
var incrOrDecrOpt = new NonTerminal("Incr Or Decr Opt");
var preIncrDecrExpression = new NonTerminal("Pre Incr Decr Expression");
var postIncrDecrExpression = new NonTerminal("Post Incr Decr Expression");
var expression = new NonTerminal("Expression");
var primaryExpression = new NonTerminal("Primary Expression");
var listLiteral = new NonTerminal("List Literal");
var unaryOperator = new NonTerminal("Unary Operator");
var unaryExpression = new NonTerminal("Unary Expression");
var spliceExpression = new NonTerminal("Splice Expression");
var listMemberExpression = new NonTerminal("List Member Expression");
var listMemberExpressionListOpt = new NonTerminal("List Member Expression List Optional");
var binOpExpression = new NonTerminal("Binary Operation Expression");
var binOp = new NonTerminal("Binary Operator", "operator symbol");
var statement = new NonTerminal("Statement");
var simpleStatement = new NonTerminal("Simple Statement");
var simpleStatementOpt = new NonTerminal("Simple Statement Optional");
var statementList = new NonTerminal("Statement List");
var CodeBody = new NonTerminal("Code Body");
#endregion
RegisterOperators(1, "||");
RegisterOperators(2, "&&");
RegisterOperators(4, "^");
RegisterOperators(6, "==", "!=");
RegisterOperators(7, "<", ">", "<=", ">=");
RegisterOperators(8, "<<", ">>");
RegisterOperators(9, " ", "-");
RegisterOperators(10, "*", "/", "%");
RegisterOperators(11, ".", ":", "in", "@");
RegisterOperators(12, " ", "--");
RegisterOperators(-3, "=", " =", "-=", "*=", "/=", "%=", "&=", "|=", "^=", "<<=", ">>=");
RegisterOperators(-2, "?");
this.MarkPunctuation(";", ",", "(", ")", "{", "}", "[", "]");
Root = CodeBody;
expression.Rule = primaryExpression | binOpExpression;
spliceExpression.Rule = at expression;
listMemberExpression.Rule = spliceExpression | expression;
listMemberExpressionListOpt.Rule = MakeStarRule(listMemberExpressionListOpt, comma, listMemberExpression);
listLiteral.Rule = lcbr listMemberExpressionListOpt rcbr;
literal.Rule = stringLiteral | error | objectLiteral | number | "true" | "false" | listLiteral;
incrOrDecrOpt.Rule = Empty | ToTerm(" ") | "--";
incrOrDecr.Rule = ToTerm(" ") | "--";
preIncrDecrExpression.Rule = incrOrDecr expression;
postIncrDecrExpression.Rule = expression incrOrDecr;
binOp.Rule = ToTerm("<") | "||" | "&&" | "^" | "==" | "!=" | ">" | "<=" | ">=" | "<<" | ">>" | " " | "-" | "*" | "/" | "%" | "in";
binOpExpression.Rule = expression binOp expression;
primaryExpression.Rule =
identifier
| unaryExpression
| preIncrDecrExpression
| postIncrDecrExpression
| literal;
unaryOperator.Rule = ToTerm(" ") | "-" | "!" | "~" | "*";
unaryExpression.Rule = unaryOperator primaryExpression;
simpleStatementOpt.Rule = expression | Empty;
simpleStatement.Rule = simpleStatementOpt semi;
statement.Rule = simpleStatement;
statementList.Rule = MakePlusRule(statementList, null, statement);
CodeBody.Rule = Empty | statementList;
}
}
}
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