Enhance context output of UnrecognizedToken exception - Githubissues

hoaproject / Compiler

The Hoa\Compiler library.

https://hoa-project.net/

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Enhance context output of UnrecognizedToken exception #111

Open ohader opened 3 years ago

ohader commented 3 years ago

Grammar

%pragma     parser.lookahead    0
%skip       space               \s
%token a    a+
%token b    b+
%token c    c+
#root:
    ( <a> | <b> | <c> )*

Source

a
b
c
d

Results

Parsing above scenario leads to expected exception, since lexeme d is not defined in grammar. In thrown UnrecognizedToken

line & column can be enhanced

(helpful) position pointer can be adjusted

Hoa\Compiler\Exception\UnrecognizedToken: Unrecognized token "d" at line 1 and column 7:
a
b
c
d
  ↑ in /Users/olly/Development/Packages/fluid-compiler/vendor/hoa/compiler/Llk/Lexer.php on line 1

With adjustments

Hoa\Compiler\Exception\UnrecognizedToken: Unrecognized token "d" at line 4 and column 1:
a
b
c
d
↑ in /Users/olly/Development/Packages/fluid-compiler/vendor/hoa/compiler/Llk/Lexer.php on line 1