Module: Antelope::Grammar::Precedences
- Included in:
- Antelope::Grammar
- Defined in:
- lib/antelope/grammar/precedences.rb
Overview
Manages precedence for tokens.
Instance Method Summary collapse
-
#generate_precedence ⇒ Array<Ace::Precedence>
private
Generates the precedence rules.
-
#precedence ⇒ Array<Ace::Precedence>
Accesses the generated precedence list.
-
#precedence_for(token) ⇒ Ace::Precedence
Finds a precedence rule for a given token.
Instance Method Details
#generate_precedence ⇒ Array<Ace::Precedence> (private)
Generates the precedence rules. Loops through the compiler
given precedence settings, and then adds two default
precedence rules; one for :$
(level 0, nonassoc), and one
for :_
(level 1, nonassoc).
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# File 'lib/antelope/grammar/precedences.rb', line 43 def generate_precedence size = @compiler.[:prec].size + 1 index = 0 precedence = [] while index < size - 1 prec = @compiler.[:prec][index] precedence << Precedence.new(prec[0], prec[1..-1].to_set, size - index) index += 1 end precedence << Precedence.new(:nonassoc, [:$end].to_set, 0) << Precedence.new(:nonassoc, [:_].to_set, 1) precedence.sort_by(&:level).reverse end |
#precedence ⇒ Array<Ace::Precedence>
Accesses the generated precedence list. Lazily generates the precedence rules on the go, and then caches it.
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# File 'lib/antelope/grammar/precedences.rb', line 13 def precedence @_precedence ||= generate_precedence end |
#precedence_for(token) ⇒ Ace::Precedence
Finds a precedence rule for a given token. If no direct
rule is defined for that token, it will check for a rule
defined for the special symbol, :_
. By default, there
is always a rule defined for :_
.
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# File 'lib/antelope/grammar/precedences.rb', line 24 def precedence_for(token) token = token.name if token.is_a?(Token) prec = precedence. detect { |pr| pr.tokens.include?(token) } || precedence. detect { |pr| pr.tokens.include?(:_) } prec end |