soml-parser/lib/parser

Parser

This includes the parser and generated ast.

Parslet is really great in that it:

• does not generate code but instean gives a clean dsl to define a grammar
• uses ruby modules so one can split the grammars up
• has support for binary operators with presedence and binding
• has a seperate tranform stage to generate an ast layer

Especially the last point is great. Since it is seperate it does not clutter up the actual grammar. And it can generate a layer that has no links to the actual parser anymore, thus saving/automating a complete tranformation process.

Operator list from http://stackoverflow.com/questions/21060234/ruby-operator-precedence-table

N A M Operator(s) Description

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1 R Y ! ~ + boolean NOT, bitwise complement, unary plus (unary plus may be redefined from Ruby 1.9 with +@)

2 R Y ** exponentiation 1 R Y - unary minus (redefine with -@)

2 L Y * / % multiplication, division, modulo (remainder) 2 L Y + - addition (or concatenation), subtraction

2 L Y << >> bitwise shift-left (or append), bitwise shift-right 2 L Y & bitwise AND

2 L Y | ^ bitwise OR, bitwise XOR (exclusive OR) 2 L Y < <= >= > ordering

2 N Y == === != =~ !~ <=> equality, pattern matching, comparison (!= and !~ may not be redefined prior to Ruby 1.9)

2 L N && boolean AND 2 L N || boolean OR

2 N N .. ... range creation (inclusive and exclusive) and boolean flip-flops

3 R N ? : ternary if-then-else (conditional) 2 L N rescue exception-handling modifier

2 R N = assignment 2 R N **= *= /= %= += -= assignment 2 R N <<= >>= assignment 2 R N &&= &= ||= |= ^= assignment

1 N N defined? test variable definition and type 1 R N not boolean NOT (low precedence) 2 L N and or boolean AND, boolean OR (low precedence) 2 N N if unless while until conditional and loop modifiers