# class SyntaxSuggest::CleanDocument

Parses and sanitizes source into a lexically aware document

Internally the document is represented by an array with each index containing a `CodeLine` correlating to a line from the source code.

There are three main phases in the algorithm:

1. Sanitize/format input source

2. Search for invalid blocks

3. Format invalid blocks into something meaninful

This class handles the first part.

The reason this class exists is to format input source for better/easier/cleaner exploration.

The `CodeSearch` class operates at the line level so we must be careful to not introduce lines that look valid by themselves, but when removed will trigger syntax errors or strange behavior.

## Join Trailing slashes

Code with a trailing slash is logically treated as a single line:

    1 it "code can be split" \
    2    "across multiple lines" do

In this case removing line 2 would add a syntax error. We get around this by internally joining the two lines into a single “line” object

## Logically Consecutive lines

Code that can be broken over multiple lines such as method calls are on different lines:

    1 User.
    2   where(name: "schneems").
    3   first

Removing line 2 can introduce a syntax error. To fix this, all lines are joined into one.

## Heredocs

A heredoc is an way of defining a multi-line string. They can cause many problems. If left as a single line, the parser would try to parse the contents as ruby code rather than as a string. Even without this problem, we still hit an issue with indentation:

    1 foo = <<~HEREDOC
    2  "Be yourself; everyone else is already taken.""
    3    ― Oscar Wilde
    4      puts "I look like ruby code" # but i'm still a heredoc
    5 HEREDOC

If we didn’t join these lines then our algorithm would think that line 4 is separate from the rest, has a higher indentation, then look at it first and remove it.

If the code evaluates line 5 by itself it will think line 5 is a constant, remove it, and introduce a syntax errror.

All of these problems are fixed by joining the whole heredoc into a single line.

## Comments and whitespace

Comments can throw off the way the lexer tells us that the line logically belongs with the next line. This is valid ruby but results in a different lex output than before:

    1 User.
    2   where(name: "schneems").
    3   # Comment here
    4   first

To handle this we can replace comment lines with empty lines and then re-lex the source. This removal and re-lexing preserves line index and document size, but generates an easier to work with document.

### Public Class Methods

new(source:) click to toggle source

    # File lib/syntax_suggest/clean_document.rb, line 87
    def initialize(source:)
      lines = clean_sweep(source: source)
      @document = CodeLine.from_source(lines.join, lines: lines)
    end

### Public Instance Methods

call() click to toggle source

Call all of the document “cleaners” and return self

    # File lib/syntax_suggest/clean_document.rb, line 94
    def call
      join_trailing_slash!
      join_consecutive!
      join_heredoc!

      self
    end

clean_sweep(source:) click to toggle source

Remove comments

replace with empty newlines

    source = <<~'EOM'
      # Comment 1
      puts "hello"
      # Comment 2
      puts "world"
    EOM

    lines = CleanDocument.new(source: source).lines
    expect(lines[0].to_s).to eq("\n")
    expect(lines[1].to_s).to eq("puts "hello")
    expect(lines[2].to_s).to eq("\n")
    expect(lines[3].to_s).to eq("puts "world")

Important: This must be done before lexing.

After this change is made, we lex the document because removing comments can change how the doc is parsed.

For example:

    values = LexAll.new(source: <<~EOM))
      User.
        # comment
        where(name: 'schneems')
    EOM
    expect(
      values.count {|v| v.type == :on_ignored_nl}
    ).to eq(1)

After the comment is removed:

     values = LexAll.new(source: <<~EOM))
       User.

         where(name: 'schneems')
     EOM
     expect(
      values.count {|v| v.type == :on_ignored_nl}
    ).to eq(2)

    # File lib/syntax_suggest/clean_document.rb, line 157
    def clean_sweep(source:)
      # Match comments, but not HEREDOC strings with #{variable} interpolation
      # https://rubular.com/r/HPwtW9OYxKUHXQ
      source.lines.map do |line|
        if line.match?(/^\s*#([^{].*|)$/)
          $/
        else
          line
        end
      end
    end

join_consecutive!() click to toggle source

Smushes logically “consecutive” lines

    source = <<~'EOM'
      User.
        where(name: 'schneems').
        first
    EOM

    lines = CleanDocument.new(source: source).join_consecutive!.lines
    expect(lines[0].to_s).to eq(source)
    expect(lines[1].to_s).to eq("")

The one known case this doesn’t handle is:

    Ripper.lex <<~EOM
      a &&
       b ||
       c
    EOM

For some reason this introduces ‘on_ignore_newline` but with BEG type

    # File lib/syntax_suggest/clean_document.rb, line 225
    def join_consecutive!
      consecutive_groups = @document.select(&:ignore_newline_not_beg?).map do |code_line|
        take_while_including(code_line.index..) do |line|
          line.ignore_newline_not_beg?
        end
      end

      join_groups(consecutive_groups)
      self
    end

join_groups(groups) click to toggle source

Helper method for joining “groups” of lines

Input is expected to be type `Array`<Array<CodeLine>>

The outer array holds the various “groups” while the inner array holds code lines.

All code lines are “joined” into the first line in their group.

To preserve document size, empty lines are placed in the place of the lines that were “joined”

    # File lib/syntax_suggest/clean_document.rb, line 266
    def join_groups(groups)
      groups.each do |lines|
        line = lines.first

        # Handle the case of multiple groups in a row
        # if one is already replaced, move on
        next if @document[line.index].empty?

        # Join group into the first line
        @document[line.index] = CodeLine.new(
          lex: lines.map(&:lex).flatten,
          line: lines.join,
          index: line.index
        )

        # Hide the rest of the lines
        lines[1..].each do |line|
          # The above lines already have newlines in them, if add more
          # then there will be double newline, use an empty line instead
          @document[line.index] = CodeLine.new(line: "", index: line.index, lex: [])
        end
      end
      self
    end

join_heredoc!() click to toggle source

Smushes all heredoc lines into one line

    source = <<~'EOM'
      foo = <<~HEREDOC
         lol
         hehehe
      HEREDOC
    EOM

    lines = CleanDocument.new(source: source).join_heredoc!.lines
    expect(lines[0].to_s).to eq(source)
    expect(lines[1].to_s).to eq("")

    # File lib/syntax_suggest/clean_document.rb, line 181
    def join_heredoc!
      start_index_stack = []
      heredoc_beg_end_index = []
      lines.each do |line|
        line.lex.each do |lex_value|
          case lex_value.type
          when :on_heredoc_beg
            start_index_stack << line.index
          when :on_heredoc_end
            start_index = start_index_stack.pop
            end_index = line.index
            heredoc_beg_end_index << [start_index, end_index]
          end
        end
      end

      heredoc_groups = heredoc_beg_end_index.map { |start_index, end_index| @document[start_index..end_index] }

      join_groups(heredoc_groups)
      self
    end

join_trailing_slash!() click to toggle source

Join lines with a trailing slash

    source = <<~'EOM'
      it "code can be split" \
         "across multiple lines" do
    EOM

    lines = CleanDocument.new(source: source).join_consecutive!.lines
    expect(lines[0].to_s).to eq(source)
    expect(lines[1].to_s).to eq("")

    # File lib/syntax_suggest/clean_document.rb, line 246
    def join_trailing_slash!
      trailing_groups = @document.select(&:trailing_slash?).map do |code_line|
        take_while_including(code_line.index..) { |x| x.trailing_slash? }
      end
      join_groups(trailing_groups)
      self
    end

lines() click to toggle source

Return an array of CodeLines in the document

    # File lib/syntax_suggest/clean_document.rb, line 104
    def lines
      @document
    end

take_while_including(range = 0..) { |line)| ... } click to toggle source

Helper method for grabbing elements from document

Like ‘take_while` except when it stops iterating, it also returns the line that caused it to stop

    # File lib/syntax_suggest/clean_document.rb, line 296
    def take_while_including(range = 0..)
      take_next_and_stop = false
      @document[range].take_while do |line|
        next if take_next_and_stop

        take_next_and_stop = !(yield line)
        true
      end
    end

to_s() click to toggle source

Renders the document back to a string

    # File lib/syntax_suggest/clean_document.rb, line 109
    def to_s
      @document.join
    end