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lex_compat.rb
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lex_compat.rb
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# frozen_string_literal: true
require "delegate"
module YARP
# This class is responsible for lexing the source using YARP and then
# converting those tokens to be compatible with Ripper. In the vast majority
# of cases, this is a one-to-one mapping of the token type. Everything else
# generally lines up. However, there are a few cases that require special
# handling.
class LexCompat
# This is a mapping of YARP token types to Ripper token types. This is a
# many-to-one mapping because we split up our token types, whereas Ripper
# tends to group them.
RIPPER = {
AMPERSAND: :on_op,
AMPERSAND_AMPERSAND: :on_op,
AMPERSAND_AMPERSAND_EQUAL: :on_op,
AMPERSAND_DOT: :on_op,
AMPERSAND_EQUAL: :on_op,
BACK_REFERENCE: :on_backref,
BACKTICK: :on_backtick,
BANG: :on_op,
BANG_EQUAL: :on_op,
BANG_TILDE: :on_op,
BRACE_LEFT: :on_lbrace,
BRACE_RIGHT: :on_rbrace,
BRACKET_LEFT: :on_lbracket,
BRACKET_LEFT_ARRAY: :on_lbracket,
BRACKET_LEFT_RIGHT: :on_op,
BRACKET_LEFT_RIGHT_EQUAL: :on_op,
BRACKET_RIGHT: :on_rbracket,
CARET: :on_op,
CARET_EQUAL: :on_op,
CHARACTER_LITERAL: :on_CHAR,
CLASS_VARIABLE: :on_cvar,
COLON: :on_op,
COLON_COLON: :on_op,
COMMA: :on_comma,
COMMENT: :on_comment,
CONSTANT: :on_const,
DOT: :on_period,
DOT_DOT: :on_op,
DOT_DOT_DOT: :on_op,
EMBDOC_BEGIN: :on_embdoc_beg,
EMBDOC_END: :on_embdoc_end,
EMBDOC_LINE: :on_embdoc,
EMBEXPR_BEGIN: :on_embexpr_beg,
EMBEXPR_END: :on_embexpr_end,
EMBVAR: :on_embvar,
EOF: :on_eof,
EQUAL: :on_op,
EQUAL_EQUAL: :on_op,
EQUAL_EQUAL_EQUAL: :on_op,
EQUAL_GREATER: :on_op,
EQUAL_TILDE: :on_op,
FLOAT: :on_float,
GREATER: :on_op,
GREATER_EQUAL: :on_op,
GREATER_GREATER: :on_op,
GREATER_GREATER_EQUAL: :on_op,
GLOBAL_VARIABLE: :on_gvar,
HEREDOC_END: :on_heredoc_end,
HEREDOC_START: :on_heredoc_beg,
IDENTIFIER: :on_ident,
IGNORED_NEWLINE: :on_ignored_nl,
IMAGINARY_NUMBER: :on_imaginary,
INTEGER: :on_int,
INSTANCE_VARIABLE: :on_ivar,
INVALID: :INVALID,
KEYWORD___ENCODING__: :on_kw,
KEYWORD___LINE__: :on_kw,
KEYWORD___FILE__: :on_kw,
KEYWORD_ALIAS: :on_kw,
KEYWORD_AND: :on_kw,
KEYWORD_BEGIN: :on_kw,
KEYWORD_BEGIN_UPCASE: :on_kw,
KEYWORD_BREAK: :on_kw,
KEYWORD_CASE: :on_kw,
KEYWORD_CLASS: :on_kw,
KEYWORD_DEF: :on_kw,
KEYWORD_DEFINED: :on_kw,
KEYWORD_DO: :on_kw,
KEYWORD_DO_LOOP: :on_kw,
KEYWORD_ELSE: :on_kw,
KEYWORD_ELSIF: :on_kw,
KEYWORD_END: :on_kw,
KEYWORD_END_UPCASE: :on_kw,
KEYWORD_ENSURE: :on_kw,
KEYWORD_FALSE: :on_kw,
KEYWORD_FOR: :on_kw,
KEYWORD_IF: :on_kw,
KEYWORD_IF_MODIFIER: :on_kw,
KEYWORD_IN: :on_kw,
KEYWORD_MODULE: :on_kw,
KEYWORD_NEXT: :on_kw,
KEYWORD_NIL: :on_kw,
KEYWORD_NOT: :on_kw,
KEYWORD_OR: :on_kw,
KEYWORD_REDO: :on_kw,
KEYWORD_RESCUE: :on_kw,
KEYWORD_RESCUE_MODIFIER: :on_kw,
KEYWORD_RETRY: :on_kw,
KEYWORD_RETURN: :on_kw,
KEYWORD_SELF: :on_kw,
KEYWORD_SUPER: :on_kw,
KEYWORD_THEN: :on_kw,
KEYWORD_TRUE: :on_kw,
KEYWORD_UNDEF: :on_kw,
KEYWORD_UNLESS: :on_kw,
KEYWORD_UNLESS_MODIFIER: :on_kw,
KEYWORD_UNTIL: :on_kw,
KEYWORD_UNTIL_MODIFIER: :on_kw,
KEYWORD_WHEN: :on_kw,
KEYWORD_WHILE: :on_kw,
KEYWORD_WHILE_MODIFIER: :on_kw,
KEYWORD_YIELD: :on_kw,
LABEL: :on_label,
LABEL_END: :on_label_end,
LAMBDA_BEGIN: :on_tlambeg,
LESS: :on_op,
LESS_EQUAL: :on_op,
LESS_EQUAL_GREATER: :on_op,
LESS_LESS: :on_op,
LESS_LESS_EQUAL: :on_op,
MINUS: :on_op,
MINUS_EQUAL: :on_op,
MINUS_GREATER: :on_tlambda,
NEWLINE: :on_nl,
NUMBERED_REFERENCE: :on_backref,
PARENTHESIS_LEFT: :on_lparen,
PARENTHESIS_LEFT_PARENTHESES: :on_lparen,
PARENTHESIS_RIGHT: :on_rparen,
PERCENT: :on_op,
PERCENT_EQUAL: :on_op,
PERCENT_LOWER_I: :on_qsymbols_beg,
PERCENT_LOWER_W: :on_qwords_beg,
PERCENT_LOWER_X: :on_backtick,
PERCENT_UPPER_I: :on_symbols_beg,
PERCENT_UPPER_W: :on_words_beg,
PIPE: :on_op,
PIPE_EQUAL: :on_op,
PIPE_PIPE: :on_op,
PIPE_PIPE_EQUAL: :on_op,
PLUS: :on_op,
PLUS_EQUAL: :on_op,
QUESTION_MARK: :on_op,
RATIONAL_NUMBER: :on_rational,
REGEXP_BEGIN: :on_regexp_beg,
REGEXP_END: :on_regexp_end,
SEMICOLON: :on_semicolon,
SLASH: :on_op,
SLASH_EQUAL: :on_op,
STAR: :on_op,
STAR_EQUAL: :on_op,
STAR_STAR: :on_op,
STAR_STAR_EQUAL: :on_op,
STRING_BEGIN: :on_tstring_beg,
STRING_CONTENT: :on_tstring_content,
STRING_END: :on_tstring_end,
SYMBOL_BEGIN: :on_symbeg,
TILDE: :on_op,
UCOLON_COLON: :on_op,
UDOT_DOT: :on_op,
UDOT_DOT_DOT: :on_op,
UMINUS: :on_op,
UMINUS_NUM: :on_op,
UPLUS: :on_op,
USTAR: :on_op,
USTAR_STAR: :on_op,
WORDS_SEP: :on_words_sep,
__END__: :on___end__
}.freeze
# When we produce tokens, we produce the same arrays that Ripper does.
# However, we add a couple of convenience methods onto them to make them a
# little easier to work with. We delegate all other methods to the array.
class Token < SimpleDelegator
def location
self[0]
end
def event
self[1]
end
def value
self[2]
end
def state
self[3]
end
end
# Ripper doesn't include the rest of the token in the event, so we need to
# trim it down to just the content on the first line when comparing.
class EndContentToken < Token
def ==(other)
[self[0], self[1], self[2][0..self[2].index("\n")], self[3]] == other
end
end
# It is extremely non obvious which state the parser is in when comments get
# dispatched. Because of this we don't both comparing state when comparing
# against other comment tokens.
class CommentToken < Token
def ==(other)
self[0...-1] == other[0...-1]
end
end
# Heredoc end tokens are emitted in an odd order, so we don't compare the
# state on them.
class HeredocEndToken < Token
def ==(other)
self[0...-1] == other[0...-1]
end
end
# Ident tokens for the most part are exactly the same, except sometimes we
# know an ident is a local when ripper doesn't (when they are introduced
# through named captures in regular expressions). In that case we don't
# compare the state.
class IdentToken < Token
def ==(other)
(self[0...-1] == other[0...-1]) && (
(other[3] == Ripper::EXPR_LABEL | Ripper::EXPR_END) ||
(other[3] & Ripper::EXPR_ARG_ANY != 0)
)
end
end
# Ignored newlines can occasionally have a LABEL state attached to them, so
# we compare the state differently here.
class IgnoredNewlineToken < Token
def ==(other)
return false unless self[0...-1] == other[0...-1]
if self[4] == Ripper::EXPR_ARG | Ripper::EXPR_LABELED
other[4] & Ripper::EXPR_ARG | Ripper::EXPR_LABELED > 0
else
self[4] == other[4]
end
end
end
# A heredoc in this case is a list of tokens that belong to the body of the
# heredoc that should be appended onto the list of tokens when the heredoc
# closes.
module Heredoc
# Heredocs that are no dash or tilde heredocs are just a list of tokens.
# We need to keep them around so that we can insert them in the correct
# order back into the token stream and set the state of the last token to
# the state that the heredoc was opened in.
class PlainHeredoc
attr_reader :tokens
def initialize
@tokens = []
end
def <<(token)
tokens << token
end
def to_a
tokens
end
end
# Dash heredocs are a little more complicated. They are a list of tokens
# that need to be split on "\\\n" to mimic Ripper's behavior. We also need
# to keep track of the state that the heredoc was opened in.
class DashHeredoc
attr_reader :split, :tokens
def initialize(split)
@split = split
@tokens = []
end
def <<(token)
tokens << token
end
def to_a
embexpr_balance = 0
tokens.each_with_object([]) do |token, results|
case token.event
when :on_embexpr_beg
embexpr_balance += 1
results << token
when :on_embexpr_end
embexpr_balance -= 1
results << token
when :on_tstring_content
if embexpr_balance == 0
lineno = token[0][0]
column = token[0][1]
if split
# Split on "\\\n" to mimic Ripper's behavior. Use a lookbehind
# to keep the delimiter in the result.
token.value.split(/(?<=[^\\]\\\n)|(?<=[^\\]\\\r\n)/).each_with_index do |value, index|
column = 0 if index > 0
results << Token.new([[lineno, column], :on_tstring_content, value, token.state])
lineno += value.count("\n")
end
else
results << token
end
else
results << token
end
else
results << token
end
end
end
end
# Heredocs that are dedenting heredocs are a little more complicated.
# Ripper outputs on_ignored_sp tokens for the whitespace that is being
# removed from the output. YARP only modifies the node itself and keeps
# the token the same. This simplifies YARP, but makes comparing against
# Ripper much harder because there is a length mismatch.
#
# Fortunately, we already have to pull out the heredoc tokens in order to
# insert them into the stream in the correct order. As such, we can do
# some extra manipulation on the tokens to make them match Ripper's
# output by mirroring the dedent logic that Ripper uses.
class DedentingHeredoc
TAB_WIDTH = 8
attr_reader :tokens, :dedent_next, :dedent, :embexpr_balance
def initialize
@tokens = []
@dedent_next = true
@dedent = nil
@embexpr_balance = 0
end
# As tokens are coming in, we track the minimum amount of common leading
# whitespace on plain string content tokens. This allows us to later
# remove that amount of whitespace from the beginning of each line.
def <<(token)
case token.event
when :on_embexpr_beg, :on_heredoc_beg
@embexpr_balance += 1
when :on_embexpr_end, :on_heredoc_end
@embexpr_balance -= 1
when :on_tstring_content
if embexpr_balance == 0
token.value.split(/(?<=\n)/).each_with_index do |line, index|
next if line.strip.empty? && line.end_with?("\n")
next if !(dedent_next || index > 0)
leading = line[/\A(\s*)\n?/, 1]
next_dedent = 0
leading.each_char do |char|
if char == "\t"
next_dedent = next_dedent - (next_dedent % TAB_WIDTH) + TAB_WIDTH
else
next_dedent += 1
end
end
@dedent = [dedent, next_dedent].compact.min
end
end
end
@dedent_next = token.event == :on_tstring_content && embexpr_balance == 0
tokens << token
end
def to_a
# If every line in the heredoc is blank, we still need to split up the
# string content token into multiple tokens.
if dedent.nil?
results = []
embexpr_balance = 0
tokens.each do |token|
case token.event
when :on_embexpr_beg, :on_heredoc_beg
embexpr_balance += 1
results << token
when :on_embexpr_end, :on_heredoc_end
embexpr_balance -= 1
results << token
when :on_tstring_content
if embexpr_balance == 0
lineno = token[0][0]
column = token[0][1]
token.value.split(/(?<=\n)/).each_with_index do |value, index|
column = 0 if index > 0
results << Token.new([[lineno, column], :on_tstring_content, value, token.state])
lineno += 1
end
else
results << token
end
else
results << token
end
end
return results
end
# Otherwise, we're going to run through each token in the list and
# insert on_ignored_sp tokens for the amount of dedent that we need to
# perform. We also need to remove the dedent from the beginning of
# each line of plain string content tokens.
results = []
dedent_next = true
embexpr_balance = 0
tokens.each do |token|
# Notice that the structure of this conditional largely matches the
# whitespace calculation we performed above. This is because
# checking if the subsequent token needs to be dedented is common to
# both the dedent calculation and the ignored_sp insertion.
case token.event
when :on_embexpr_beg
embexpr_balance += 1
results << token
when :on_embexpr_end
embexpr_balance -= 1
results << token
when :on_tstring_content
if embexpr_balance == 0
# Here we're going to split the string on newlines, but maintain
# the newlines in the resulting array. We'll do that with a look
# behind assertion.
splits = token.value.split(/(?<=\n)/)
index = 0
while index < splits.length
line = splits[index]
lineno = token[0][0] + index
column = token[0][1]
# Blank lines do not count toward common leading whitespace
# calculation and do not need to be dedented.
if dedent_next || index > 0
column = 0
end
# If the dedent is 0 and we're not supposed to dedent the next
# line or this line doesn't start with whitespace, then we
# should concatenate the rest of the string to match ripper.
if dedent == 0 && (!dedent_next || !line.start_with?(/\s/))
line = splits[index..].join
index = splits.length
end
# If we are supposed to dedent this line or if this is not the
# first line of the string and this line isn't entirely blank,
# then we need to insert an on_ignored_sp token and remove the
# dedent from the beginning of the line.
if (dedent > 0) && (dedent_next || index > 0)
deleting = 0
deleted_chars = []
# Gather up all of the characters that we're going to
# delete, stopping when you hit a character that would put
# you over the dedent amount.
line.each_char.with_index do |char, i|
case char
when "\r"
if line.chars[i + 1] == "\n"
break
end
when "\n"
break
when "\t"
deleting = deleting - (deleting % TAB_WIDTH) + TAB_WIDTH
else
deleting += 1
end
break if deleting > dedent
deleted_chars << char
end
# If we have something to delete, then delete it from the
# string and insert an on_ignored_sp token.
if deleted_chars.any?
ignored = deleted_chars.join
line.delete_prefix!(ignored)
results << Token.new([[lineno, 0], :on_ignored_sp, ignored, token[3]])
column = ignored.length
end
end
results << Token.new([[lineno, column], token[1], line, token[3]]) unless line.empty?
index += 1
end
else
results << token
end
else
results << token
end
dedent_next =
((token.event == :on_tstring_content) || (token.event == :on_heredoc_end)) &&
embexpr_balance == 0
end
results
end
end
# Here we will split between the two types of heredocs and return the
# object that will store their tokens.
def self.build(opening)
case opening.value[2]
when "~"
DedentingHeredoc.new
when "-"
DashHeredoc.new(opening.value[3] != "'")
else
PlainHeredoc.new
end
end
end
attr_reader :source, :filepath
def initialize(source, filepath = "")
@source = source
@filepath = filepath || ""
end
def result
tokens = []
state = :default
heredoc_stack = [[]]
result = YARP.lex(source, @filepath)
result_value = result.value
previous_state = nil
# If there's a UTF-8 byte-order mark as the start of the file, then ripper
# sets every token's on the first line back by 6 bytes. It also keeps the
# byte order mark in the first token's value. This is weird, and I don't
# want to mirror that in our parser. So instead, we'll match up the values
# here, and then match up the locations as we process the tokens.
bom = source.bytes[0..2] == [0xEF, 0xBB, 0xBF]
result_value[0][0].value.prepend("\xEF\xBB\xBF") if bom
result_value.each_with_index do |(token, lex_state), index|
lineno = token.location.start_line
column = token.location.start_column
column -= index == 0 ? 6 : 3 if bom && lineno == 1
event = RIPPER.fetch(token.type)
value = token.value
lex_state = Ripper::Lexer::State.new(lex_state)
token =
case event
when :on___end__
EndContentToken.new([[lineno, column], event, value, lex_state])
when :on_comment
CommentToken.new([[lineno, column], event, value, lex_state])
when :on_heredoc_end
# Heredoc end tokens can be emitted in an odd order, so we don't
# want to bother comparing the state on them.
HeredocEndToken.new([[lineno, column], event, value, lex_state])
when :on_embexpr_end, :on_ident
if lex_state == Ripper::EXPR_END | Ripper::EXPR_LABEL
# In the event that we're comparing identifiers, we're going to
# allow a little divergence. Ripper doesn't account for local
# variables introduced through named captures in regexes, and we
# do, which accounts for this difference.
IdentToken.new([[lineno, column], event, value, lex_state])
else
Token.new([[lineno, column], event, value, lex_state])
end
when :on_ignored_nl
# Ignored newlines can occasionally have a LABEL state attached to
# them which doesn't actually impact anything. We don't mirror that
# state so we ignored it.
IgnoredNewlineToken.new([[lineno, column], event, value, lex_state])
when :on_regexp_end
# On regex end, Ripper scans and then sets end state, so the ripper
# lexed output is begin, when it should be end. YARP sets lex state
# correctly to end state, but we want to be able to compare against
# Ripper's lexed state. So here, if it's a regexp end token, we
# output the state as the previous state, solely for the sake of
# comparison.
previous_token = result_value[index - 1][0]
lex_state =
if RIPPER.fetch(previous_token.type) == :on_embexpr_end
# If the previous token is embexpr_end, then we have to do even
# more processing. The end of an embedded expression sets the
# state to the state that it had at the beginning of the
# embedded expression. So we have to go and find that state and
# set it here.
counter = 1
current_index = index - 1
until counter == 0
current_index -= 1
current_event = RIPPER.fetch(result_value[current_index][0].type)
counter += { on_embexpr_beg: -1, on_embexpr_end: 1 }[current_event] || 0
end
Ripper::Lexer::State.new(result_value[current_index][1])
else
previous_state
end
Token.new([[lineno, column], event, value, lex_state])
else
Token.new([[lineno, column], event, value, lex_state])
end
previous_state = lex_state
# The order in which tokens appear in our lexer is different from the
# order that they appear in Ripper. When we hit the declaration of a
# heredoc in YARP, we skip forward and lex the rest of the content of
# the heredoc before going back and lexing at the end of the heredoc
# identifier.
#
# To match up to ripper, we keep a small state variable around here to
# track whether we're in the middle of a heredoc or not. In this way we
# can shuffle around the token to match Ripper's output.
case state
when :default
tokens << token
if event == :on_heredoc_beg
state = :heredoc_opened
heredoc_stack.last << Heredoc.build(token)
end
when :heredoc_opened
heredoc_stack.last.last << token
case event
when :on_heredoc_beg
heredoc_stack << [Heredoc.build(token)]
when :on_heredoc_end
state = :heredoc_closed
end
when :heredoc_closed
if %i[on_nl on_ignored_nl on_comment].include?(event) || (event == :on_tstring_content && value.end_with?("\n"))
if heredoc_stack.size > 1
flushing = heredoc_stack.pop
heredoc_stack.last.last << token
flushing.each do |heredoc|
heredoc.to_a.each do |flushed_token|
heredoc_stack.last.last << flushed_token
end
end
state = :heredoc_opened
next
end
elsif event == :on_heredoc_beg
tokens << token
state = :heredoc_opened
heredoc_stack.last << Heredoc.build(token)
next
elsif heredoc_stack.size > 1
heredoc_stack[-2].last << token
next
end
heredoc_stack.last.each do |heredoc|
tokens.concat(heredoc.to_a)
end
heredoc_stack.last.clear
state = :default
tokens << token
end
end
tokens.reject! { |t| t.event == :on_eof }
# We sort by location to compare against Ripper's output
tokens.sort_by!(&:location)
if result_value.size - 1 > tokens.size
raise StandardError, "Lost tokens when performing lex_compat"
end
ParseResult.new(tokens, result.comments, result.errors, result.warnings, [])
end
end
# The constant that wraps the behavior of the lexer to match Ripper's output
# is an implementation detail, so we don't want it to be public.
private_constant :LexCompat
# Returns an array of tokens that closely resembles that of the Ripper lexer.
# The only difference is that since we don't keep track of lexer state in the
# same way, it's going to always return the NONE state.
def self.lex_compat(source, filepath = "")
LexCompat.new(source, filepath).result
end
# This lexes with the Ripper lex. It drops any space events but otherwise
# returns the same tokens. Raises SyntaxError if the syntax in source is
# invalid.
def self.lex_ripper(source)
previous = []
results = []
Ripper.lex(source, raise_errors: true).each do |token|
case token[1]
when :on_sp
# skip
when :on_tstring_content
if previous[1] == :on_tstring_content &&
(token[2].start_with?("\#$") || token[2].start_with?("\#@"))
previous[2] << token[2]
else
results << token
previous = token
end
when :on_words_sep
if previous[1] == :on_words_sep
previous[2] << token[2]
else
results << token
previous = token
end
else
results << token
previous = token
end
end
results
end
end