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Contents
module JsDuck
module Js
# Evaluates Esprima AST node into Ruby object
class Evaluator
# Converts AST node into a value.
#
# - String literals become Ruby strings
# - Number literals become Ruby numbers
# - Regex literals become :regexp symbols
# - Array expressions become Ruby arrays
# - etc
#
# For anything it doesn't know how to evaluate (like a function
# expression) it throws exception.
#
def to_value(ast)
case ast["type"]
when "ArrayExpression"
ast["elements"].map {|e| to_value(e) }
when "ObjectExpression"
h = {}
ast["properties"].each do |p|
key = key_value(p["key"])
value = to_value(p["value"])
h[key] = value
end
h
when "BinaryExpression"
if ast["operator"] == "+"
to_value(ast["left"]) + to_value(ast["right"])
else
throw "Unable to handle operator: " + ast["operator"]
end
when "MemberExpression"
if base_css_prefix?(ast)
"x-"
else
throw "Unable to handle this MemberExpression"
end
when "Literal"
if ast["raw"] =~ /\A\//
:regexp
else
ast["value"]
end
else
throw "Unknown node type: " + ast["type"]
end
end
# Turns object property key into string value
def key_value(key)
key["type"] == "Identifier" ? key["name"] : key["value"]
end
# True when MemberExpression == Ext.baseCSSPrefix
def base_css_prefix?(ast)
ast["computed"] == false &&
ast["object"]["type"] == "Identifier" &&
ast["object"]["name"] == "Ext" &&
ast["property"]["type"] == "Identifier" &&
ast["property"]["name"] == "baseCSSPrefix"
end
end
end
end
Version data entries
30 entries across 30 versions & 3 rubygems