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#43 in Parser tooling

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Apache-2.0/MIT

445KB
9K SLoC

nimbleparse

nimbleparse is a simple grammar debugging aid. It takes as input a Lex specification, a Yacc specification, and an input file and prints any warnings about the specifications (e.g. shift/reduce errors) as well as the resulting parse tree to stdout. If the parse is unsuccessful it will report parsing errors and, when possible fixes. If parsing is successful, nimbleparse exits with 0; if an error is detected it exits with 1.

The full command-line specification is as follows:

nimbleparse [-r <cpctplus|none>] [-y <eco|grmtools|original>] [-q] <lexer.l> <parser.y> <input file>

where:

  • -r selects the recovery algorithm to be used. Defaults to cpctplus.
  • -y selects the Yacc variant to be used. Defaults to original.
  • -q prevents warnings (e.g. shift/reduce errors) from being reported.

You can use your own Lex/Yacc files. A small repository of example grammars can be found at https://github.com/softdevteam/grammars/.

An example invocation is as follows:

$ cat Hello.java
class Hello {
    public static void main(String[] args) {
        System.out.println("Hello world");
    }
}
$ nimbleparse java7.l java7.y Hello.java
goal
 compilation_unit
  type_declarations_opt
   type_declarations
    type_declaration
     class_declaration
      modifiers_opt
      CLASS class
      IDENTIFIER Hello
      type_parameters_opt
      super_opt
      interfaces_opt
      class_body
       LBRACE {
       class_body_declarations_opt
        class_body_declarations
         class_body_declaration
          class_member_declaration
           method_declaration
            method_header
             modifiers_opt
              modifiers
               modifiers
                modifier
                 PUBLIC public
               modifier
                STATIC static
             VOID void
             method_declarator
              IDENTIFIER main
              LPAREN (
              formal_parameter_list_opt
               formal_parameter_list
                formal_parameter
                 type
                  reference_type
                   array_type
                    name
                     simple_name
                      IDENTIFIER String
                    dims
                     LBRACK [
                     RBRACK ]
                 variable_declarator_id
                  IDENTIFIER args
              RPAREN )
             throws_opt
            method_body
             block
              LBRACE {
              block_statements_opt
               block_statements
                block_statement
                 statement
                  statement_without_trailing_substatement
                   expression_statement
                    statement_expression
                     method_invocation
                      qualified_name
                       name
                        qualified_name
                         name
                          simple_name
                           IDENTIFIER System
                         DOT .
                         IDENTIFIER out
                       DOT .
                       IDENTIFIER println
                      LPAREN (
                      argument_list_opt
                       argument_list
                        expression
                         assignment_expression
                          conditional_expression
                           conditional_or_expression
                            conditional_and_expression
                             inclusive_or_expression
                              exclusive_or_expression
                               and_expression
                                equality_expression
                                 instanceof_expression
                                  relational_expression
                                   shift_expression
                                    additive_expression
                                     multiplicative_expression
                                      unary_expression
                                       unary_expression_not_plus_minus
                                        postfix_expression
                                         primary
                                          primary_no_new_array
                                           literal
                                            STRING_LITERAL "Hello world"
                      RPAREN )
                    SEMICOLON ;
              RBRACE }
       RBRACE }
$ cat SyntaxError.java
class SyntaxError {
    int x y;
}
$ nimbleparse java7.l java7.y Hello.java
goal
 compilation_unit
  type_declarations_opt
   type_declarations
    type_declaration
     class_declaration
      modifiers_opt
      CLASS class
      IDENTIFIER SyntaxError
      type_parameters_opt
      super_opt
      interfaces_opt
      class_body
       LBRACE {
       class_body_declarations_opt
        class_body_declarations
         class_body_declaration
          class_member_declaration
           field_declaration
            modifiers_opt
            type
             primitive_type
              numeric_type
               integral_type
                INT int
            variable_declarators
             variable_declarators
              variable_declarator
               variable_declarator_id
                IDENTIFIER x
             COMMA 
             variable_declarator
              variable_declarator_id
               IDENTIFIER y
            SEMICOLON ;
       RBRACE }

Parsing error at line 2 column 11. Repair sequences found:
   1: Insert ,
   2: Insert =
   3: Delete y

Dependencies

~2.5–4MB
~91K SLoC