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:
-
Sanitize/format input source
-
Search for invalid blocks
-
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.
# File tmp/rubies/ruby-master/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
# File tmp/rubies/ruby-master/lib/syntax_suggest/clean_document.rb, line 94
def call
join_trailing_slash!
join_consecutive!
join_heredoc!
self
end
Call all of the document “cleaners” and return self
# File tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/lib/syntax_suggest/clean_document.rb, line 104
def lines
@document
end
Return an array of CodeLines in the document
# File tmp/rubies/ruby-master/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
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 tmp/rubies/ruby-master/lib/syntax_suggest/clean_document.rb, line 109
def to_s
@document.join
end
Renders the document back to a string