Project Lolita

Overview

Project Lolita is an exprimental lexer and parser generator that supports parser generation with minimal regular expression and LALR(1) grammar. With a builtin AST construction engine, the syntax tree Project Lolita produce is automatically folded on grammar reduction and a visitor interface for klasses of the same category is also generated to ease the postprocess of the parsing tree.

License

This is a personal project released in MIT license. You may feel free to read, copy, modify and distribute the code, but reliability is ABSOLUTELY NOT GUARANTEED. Any help and question on the project is welcomed.

Example Usage

# This is a example file of Project Lolita
# that parses a list of simple calculator expressions

ignore whitespace = "[ \t\r\n]+";
token int = "[0-9]+";
token op_add = "\+";
token op_minus = "-";
token op_asterisk = "\*";
token op_slash = "/";
token lp = "\(";
token rp = "\)";
token lb = "\[";
token rb = "\]";
token comma = ",";

enum BinaryOp { Plus; Minus; Asterisk; Slash; }

base Expression;
node LiteralExpression : Expression
{
    token value;
}
node BinaryExpression : Expression
{
    Expression lhs;
    BinaryOp op;
    Expression rhs;
}

rule AddOp : BinaryOp
    = "\+" -> Plus
    = "-" -> Minus
    ;
rule MulOp : BinaryOp
    = "\*" -> Asterisk
    = "/" -> Slash
    ;

rule Factor : Expression
    = int:value -> LiteralExpression
    = lp Expr! rp
    ;
rule MulExpr : BinaryExpression
    = MulExpr:lhs MulOp:op Factor:rhs -> _
    = Factor!
    ;
rule AddExpr : BinaryExpression
    = AddExpr:lhs AddOp:op MulExpr:rhs -> _
    = MulExpr!
    ;
rule Expr : Expression
    = AddExpr!
    ;
    
rule ExprList : Expression'vec
	= Expr& -> _
	= ExprList! comma Expr&
	;
rule InputExpr : Expression'vec
	= lb ExprList! rb
	;

# you may first call BootstrapParser(...) using this configuration file
# and in the header generated, there would be a CreateParser() function to instantiate a parser

Configuration File

TODO

• GLR support for some ambiguous grammar
• Error detection for configuration file
• Token post-processing injection
• Parsing table dump