48 lines
1.2 KiB
Ruby
48 lines
1.2 KiB
Ruby
require_relative "basic_types"
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require_relative "tokens"
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module Parser
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#obviously a work in progress !!
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# We "compose" the parser from bits, divide and hopefully conquer
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class Composed < Parslet::Parser
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include BasicTypes
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include Tokens
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rule(:args) {
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left_parenthesis >>
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((expression.as(:arg) >> (comma >> expression.as(:arg)).repeat(0)).maybe).as(:args) >>
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right_parenthesis
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}
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rule(:funcall) { name.as(:funcall) >> args }
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rule(:expression) { cond | funcall | integer | name }
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rule(:cond) {
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if_kw >> left_parenthesis >> expression.as(:cond) >> right_parenthesis >>
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body.as(:if_true) >>
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else_kw >>
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body.as(:if_false)
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}
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rule(:body) { left_brace >> expression.as(:body) >> right_brace }
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rule(:if_kw) { str('if') >> space? }
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rule(:else_kw) { str('else') >> space? }
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rule(:func) {
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func_kw >> name.as(:func) >> params >> body
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}
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rule(:func_kw) { str('function') >> space? }
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rule(:params) {
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left_parenthesis >>
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((name.as(:param) >> (comma >> name.as(:param)).repeat(0)).maybe).as(:params) >>
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right_parenthesis
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}
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rule(:root){ func.repeat(0) >> expression | expression | args }
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end
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end
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