Class: SyntaxTree::HshPtn

Inherits:
Node
  • Object
show all
Defined in:
lib/syntax_tree/node.rb

Overview

HshPtn represents matching against a hash pattern using the Ruby 2.7+ pattern matching syntax.

case value
in { key: }
end

Defined Under Namespace

Classes: KeywordFormatter, KeywordRestFormatter

Instance Attribute Summary collapse

Attributes inherited from Node

#location

Instance Method Summary collapse

Methods inherited from Node

#construct_keys, #pretty_print, #to_json

Constructor Details

#initialize(constant:, keywords:, keyword_rest:, location:, comments: []) ⇒ HshPtn

Returns a new instance of HshPtn.



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# File 'lib/syntax_tree/node.rb', line 4955

def initialize(constant:, keywords:, keyword_rest:, location:, comments: [])
  @constant = constant
  @keywords = keywords
  @keyword_rest = keyword_rest
  @location = location
  @comments = comments
end

Instance Attribute Details

#comments ⇒ Object (readonly)

Array[ Comment | EmbDoc ]

the comments attached to this node



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# File 'lib/syntax_tree/node.rb', line 4953

def comments
  @comments
end

#constant ⇒ Object (readonly)

nil | untyped

the optional constant wrapper



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# File 'lib/syntax_tree/node.rb', line 4943

def constant
  @constant
end

#keyword_rest ⇒ Object (readonly)

nil | VarField

an optional parameter to gather up all remaining keywords



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# File 'lib/syntax_tree/node.rb', line 4950

def keyword_rest
  @keyword_rest
end

#keywords ⇒ Object (readonly)

Array[ [Label, untyped

]] the set of tuples representing the keywords

that should be matched against in the pattern



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# File 'lib/syntax_tree/node.rb', line 4947

def keywords
  @keywords
end

Instance Method Details

#accept(visitor) ⇒ Object 



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# File 'lib/syntax_tree/node.rb', line 4963

def accept(visitor)
  visitor.visit_hshptn(self)
end

#child_nodes ⇒ Object Also known as: deconstruct 



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# File 'lib/syntax_tree/node.rb', line 4967

def child_nodes
  [constant, *keywords.flatten(1), keyword_rest]
end

#deconstruct_keys(_keys) ⇒ Object 



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# File 'lib/syntax_tree/node.rb', line 4973

def deconstruct_keys(_keys)
  {
    constant: constant,
    keywords: keywords,
    keyword_rest: keyword_rest,
    location: location,
    comments: comments
  }
end

#format(q) ⇒ Object 



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# File 'lib/syntax_tree/node.rb', line 4983

def format(q)
  parts = keywords.map { |(key, value)| KeywordFormatter.new(key, value) }
  parts << KeywordRestFormatter.new(keyword_rest) if keyword_rest

  nested = PATTERNS.include?(q.parent.class)
  contents = -> do
    q.group { q.seplist(parts) { |part| q.format(part, stackable: false) } }

    # If there isn't a constant, and there's a blank keyword_rest, then we
    # have an plain ** that needs to have a `then` after it in order to
    # parse correctly on the next parse.
    if !constant && keyword_rest && keyword_rest.value.nil? && !nested
      q.text(" then")
    end
  end

  # If there is a constant, we're going to format to have the constant name
  # first and then use brackets.
  if constant
    q.group do
      q.format(constant)
      q.text("[")
      q.indent do
        q.breakable("")
        contents.call
      end
      q.breakable("")
      q.text("]")
    end
    return
  end

  # If there's nothing at all, then we're going to use empty braces.
  if parts.empty?
    q.text("{}")
    return
  end

  # If there's only one pair, then we'll just print the contents provided
  # we're not inside another pattern.
  if !nested && parts.size == 1
    contents.call
    return
  end

  # Otherwise, we're going to always use braces to make it clear it's a hash
  # pattern.
  q.group do
    q.text("{")
    q.indent do
      q.breakable
      contents.call
    end
    q.breakable
    q.text("}")
  end
end