# class SyntaxSuggest::BlockExpand

This class is responsible for taking a code block that exists at a far indentaion and then iteratively increasing the block so that it captures everything within the same indentation block.

    def dog
      puts "bow"
      puts "wow"
    end

block = `BlockExpand.new`(code_lines: code_lines)

    .call(CodeBlock.new(lines: code_lines[1]))

puts block.to_s # => puts “bow”

    puts "wow"

Once a code block has captured everything at a given indentation level then it will expand to capture surrounding indentation.

block = `BlockExpand.new`(code_lines: code_lines)

    .call(block)

block.to_s # => def dog

      puts "bow"
      puts "wow"
    end

### Public Class Methods

new (code_lines:)
Source

    # File lib/syntax_suggest/block_expand.rb, line 34
    def initialize(code_lines:)
      @code_lines = code_lines
    end

### Public Instance Methods

call (block)
Source

    # File lib/syntax_suggest/block_expand.rb, line 40
    def call(block)
      if (next_block = expand_neighbors(block))
        next_block
      else
        expand_indent(block)
      end
    end

Main interface. Expand current indentation, before expanding to a lower indentation

expand_indent (block)
Source

    # File lib/syntax_suggest/block_expand.rb, line 63
    def expand_indent(block)
      now = AroundBlockScan.new(code_lines: @code_lines, block: block)
        .force_add_hidden
        .stop_after_kw
        .scan_adjacent_indent

      now.lookahead_balance_one_line

      now.code_block
    end

Expands code to the next lowest indentation

For example:

    1 def dog
    2   print "dog"
    3 end

If a block starts on line 2 then it has captured all it’s “neighbors” (code at the same indentation or higher). To continue expanding, this block must capture lines one and three which are at a different indentation level.

This method allows fully expanded blocks to decrease their indentation level (so they can expand to capture more code up and down). It does this conservatively as there’s no undo (currently).

expand_neighbors (block)
Source

    # File lib/syntax_suggest/block_expand.rb, line 130
    def expand_neighbors(block)
      now = AroundBlockScan.new(code_lines: @code_lines, block: block)

      # Initial scan
      now
        .force_add_hidden
        .stop_after_kw
        .scan_neighbors_not_empty

      # Slurp up empties
      now
        .scan_while { |line| line.empty? }

      # If next line is kw and it will balance us, take it
      expanded_lines = now
        .lookahead_balance_one_line
        .lines

      # Don't allocate a block if it won't be used
      #
      # If nothing was taken, return nil to indicate that status
      # used in `def call` to determine if
      # we need to expand up/out (`expand_indent`)
      if block.lines == expanded_lines
        nil
      else
        CodeBlock.new(lines: expanded_lines)
      end
    end

A neighbor is code that is at or above the current indent line.

First we build a block with all neighbors. If we can’t go further then we decrease the indentation threshold and expand via indentation i.e. ‘expand_indent`

Handles two general cases.

## Case #1: Check code inside of methods/classes/etc.

It’s important to note, that not everything in a given indentation level can be parsed as valid code even if it’s part of valid code. For example:

    1 hash = {
    2   name: "richard",
    3   dog: "cinco",
    4 }

In this case lines 2 and 3 will be neighbors, but they’re invalid until ‘expand_indent` is called on them.

When we are adding code within a method or class (at the same indentation level), use the empty lines to denote the programmer intended logical chunks. Stop and check each one. For example:

    1 def dog
    2   print "dog"
    3
    4   hash = {
    5 end

If we did not stop parsing at empty newlines then the block might mistakenly grab all the contents (lines 2, 3, and 4) and report them as being problems, instead of only line 4.

## Case #2: Expand/grab other logical blocks

Once the search algorithm has converted all lines into blocks at a given indentation it will then ‘expand_indent`. Once the blocks that generates are expanded as neighbors we then begin seeing neighbors being other logical blocks i.e. a block’s neighbors may be another method or class (something with keywords/ends).

For example:

    1 def bark
    2
    3 end
    4
    5 def sit
    6 end

In this case if lines 4, 5, and 6 are in a block when it tries to expand neighbors it will expand up. If it stops after line 2 or 3 it may cause problems since there’s a valid kw/end pair, but the block will be checked without it.

We try to resolve this edge case with ‘lookahead_balance_one_line` below.

inspect ()
Source

    # File lib/syntax_suggest/block_expand.rb, line 161
    def inspect
      "#<SyntaxSuggest::CodeBlock:0x0000123843lol >"
    end

Manageable rspec errors