Class: Less2Sass::Less::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/less2sass/less/parser.rb

Overview

The parser for Less. It parses a Less project into a tree of Tree::Nodes. The project is meant as one or more files.

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ Parser 



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# File 'lib/less2sass/less/parser.rb', line 11

def initialize(input)
  @input = input
  @options = input == $stdin ? "-stdin \"#{Util.read_stdin_as_multiline_arg}\"" : File.expand_path(input)
end

Instance Method Details

#build_tree(json, parent = nil) ⇒ Less2Sass::Less::Tree::Node

Converts the parsed Less project from JSON object to a Tree::Node representation.

Note, that this method recursively calls itself.

Raises:



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# File 'lib/less2sass/less/parser.rb', line 50

def build_tree(json, parent = nil)
  node = create_node(json['class'], parent)

  json.each do |k, v|
    key = instance_var_sym(k)

    if v.is_a?(Hash)
      # Is the hash a node, or a simple value?
      if node?(v)
        # The node should be referenced under the original key, as well as
        # in the child nodes, so it's easier to handle conversion
        # and still be able to traverse the full tree. Since these would be
        # the same objects, the changes made during the transformation
        # process would be reflected at both places.
        subnode = build_tree(v, node)
        node.instance_variable_set(key, subnode)
        node << subnode
      else
        node.instance_variable_set(key, v)
      end
    elsif v.is_a?(Array)
      if node?(v[0])
        # It's an array of nodes
        subnodes = []
        v.each do |item|
          # Something is very wrong if the item is not another node
          raise LessASTParserError, item.class.to_s unless node?(item)
          subnode = build_tree(item, node)
          subnodes << subnode
          node << subnode
        end
        value = subnodes.length == 1 ? subnodes[0] : subnodes
        node.instance_variable_set(key, value)
      else
        # It's a simple array containing other values than nodes
        node.instance_variable_set(key, v)
      end
    else
      # Simple key-value pair
      next if k == 'class'
      node.instance_variable_set(key, v)
    end
  end

  node
end

#check_syntax ⇒ void

This method returns an undefined value.

Checks, whether the Less project can be compiled.

Raises:



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# File 'lib/less2sass/less/parser.rb', line 20

def check_syntax
  response = `lessc --lint #{File.expand_path(@input)} 2>&1 >/dev/null`
  raise LessCompilationError, response unless response.empty?
end

#parse ⇒ Less2Sass::Less::Tree::Node

Parses a Less project.

Raises:



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# File 'lib/less2sass/less/parser.rb', line 30

def parse
  string_ast = `node #{Util.scope(PARSER)} #{@options}`
  json_ast = JSON.parse(string_ast)
  if json_ast['class'] == 'error'
    raise LessImportNotFoundError, json_ast if json_ast['type'] == 'File'
    raise LessSyntaxError, json_ast if json_ast['type'] == 'Parse'
  end
  build_tree(json_ast)
end