This class is useful for exploring contents before and after a block
It searches above and below the passed in block to match for whatever criteria you give it:
Example:
def dog # 1
puts "bark" # 2
puts "bark" # 3
end # 4
scan = AroundBlockScan.new(
code_lines: code_lines
block: CodeBlock.new(lines: code_lines[1])
)
scan.scan_while { true }
puts scan.before_index # => 0
puts scan.after_index # => 3
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 30
def initialize(code_lines:, block:)
@code_lines = code_lines
@orig_indent = block.current_indent
@stop_after_kw = false
@force_add_empty = false
@force_add_hidden = false
@target_indent = nil
@scanner = ScanHistory.new(code_lines: code_lines, block: block)
end
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 217
def code_block
CodeBlock.new(lines: lines)
end
Return the currently matched lines as a ‘CodeBlock`
When a ‘CodeBlock` is created it will gather metadata about itself, so this is not a free conversion. Avoid allocating more CodeBlock’s than needed
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 60
def force_add_empty
@force_add_empty = true
self
end
When using this flag, ‘scan_while` will bypass the block it’s given and always add a line that responds truthy to ‘CodeLine#empty?`
Empty lines contain no code, only whitespace such as leading spaces a newline.
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 49
def force_add_hidden
@force_add_hidden = true
self
end
When using this flag, ‘scan_while` will bypass the block it’s given and always add a line that responds truthy to ‘CodeLine#hidden?`
Lines are hidden when they’ve been evaluated by the parser as part of a block and found to contain valid code.
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 228
def inspect
"#<#{self.class}:0x0000123843lol >"
end
Manageable rspec errors
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 223
def lines
@scanner.lines
end
Returns the lines matched by the current scan as an array of CodeLines
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 141
def lookahead_balance_one_line
kw_count = 0
end_count = 0
lines.each do |line|
kw_count += 1 if line.is_kw?
end_count += 1 if line.is_end?
end
return self if kw_count == end_count # nothing to balance
@scanner.commit_if_changed # Rollback point if we don't find anything to optimize
# Try to eat up empty lines
@scanner.scan(
up: ->(line, _, _) { line.hidden? || line.empty? },
down: ->(line, _, _) { line.hidden? || line.empty? }
)
# More ends than keywords, check if we can balance expanding up
next_up = @scanner.next_up
next_down = @scanner.next_down
case end_count - kw_count
when 1
if next_up&.is_kw? && next_up.indent >= @target_indent
@scanner.scan(
up: ->(line, _, _) { line == next_up },
down: ->(line, _, _) { false }
)
@scanner.commit_if_changed
end
when -1
if next_down&.is_end? && next_down.indent >= @target_indent
@scanner.scan(
up: ->(line, _, _) { false },
down: ->(line, _, _) { line == next_down }
)
@scanner.commit_if_changed
end
end
# Rollback any uncommitted changes
@scanner.stash_changes
self
end
Scanning is intentionally conservative because we have no way of rolling back an aggressive block (at this time)
If a block was stopped for some trivial reason, (like an empty line) but the next line would have caused it to be balanced then we can check that condition and grab just one more line either up or down.
For example, below if we’re scanning up, line 2 might cause the scanning to stop. This is because empty lines might denote logical breaks where the user intended to chunk code which is a good place to stop and check validity. Unfortunately it also means we might have a “dangling” keyword or end.
1 def bark 2 3 end
If lines 2 and 3 are in the block, then when this method is run it would see it is unbalanced, but that acquiring line 1 would make it balanced, so that’s what it does.
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 200
def scan_adjacent_indent
before_after_indent = []
before_after_indent << (@scanner.next_up&.indent || 0)
before_after_indent << (@scanner.next_down&.indent || 0)
@target_indent = before_after_indent.min
scan_while { |line| line.not_empty? && line.indent >= @target_indent }
self
end
Scan blocks based on indentation of next line above/below block
Determines indentaion of the next line above/below the current block.
Normally this is called when a block has expanded to capture all “neighbors” at the same (or greater) indentation and needs to expand out. For example the ‘def/end` lines surrounding a method.
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 188
def scan_neighbors_not_empty
@target_indent = @orig_indent
scan_while { |line| line.not_empty? && line.indent >= @target_indent }
end
Finds code lines at the same or greater indentation and adds them to the block
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 88
def scan_while
stop_next_up = false
stop_next_down = false
@scanner.scan(
up: ->(line, kw_count, end_count) {
next false if stop_next_up
next true if @force_add_hidden && line.hidden?
next true if @force_add_empty && line.empty?
if @stop_after_kw && kw_count > end_count
stop_next_up = true
end
yield line
},
down: ->(line, kw_count, end_count) {
next false if stop_next_down
next true if @force_add_hidden && line.hidden?
next true if @force_add_empty && line.empty?
if @stop_after_kw && end_count > kw_count
stop_next_down = true
end
yield line
}
)
self
end
Main work method
The scan_while method takes a block that yields lines above and below the block. If the yield returns true, the @before_index or @after_index are modified to include the matched line.
In addition to yielding individual lines, the internals of this object give a mini DSL to handle common situations such as stopping if we’ve found a keyword/end mis-match in one direction or the other.
# File tmp/rubies/ruby-master/lib/syntax_suggest/around_block_scan.rb, line 73
def stop_after_kw
@stop_after_kw = true
self
end
Tells ‘scan_while` to look for mismatched keyword/end-s
When scanning up, if we see more keywords then end-s it will stop. This might happen when scanning outside of a method body. the first scan line up would be a keyword and this setting would trigger a stop.
When scanning down, stop if there are more end-s than keywords.