# frozen_string_literal: true
require_relative "scan_history"
module SyntaxSuggest
# 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
#
class AroundBlockScan
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
# 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.
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#empty?`
#
# Empty lines contain no code, only whitespace such
# as leading spaces a newline.
def force_add_empty
@force_add_empty = 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.
def stop_after_kw
@stop_after_kw = true
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.
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
# 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.
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
# Finds code lines at the same or greater indentation and adds them
# to the block
def scan_neighbors_not_empty
@target_indent = @orig_indent
scan_while { |line| line.not_empty? && line.indent >= @target_indent }
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.
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
# 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
def code_block
CodeBlock.new(lines: lines)
end
# Returns the lines matched by the current scan as an
# array of CodeLines
def lines
@scanner.lines
end
# Manageable rspec errors
def inspect
"#<#{self.class}:0x0000123843lol >"
end
end
end
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