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# This module is an integral part of the Lexer.
# It defines interpolation support
# PERFORMANCE NOTE: There are 4 very similar methods in this module that are designed to be as
# performant as possible. While it is possible to parameterize them into one common method, the overhead
# of passing parameters and evaluating conditional logic has a negative impact on performance.
#
module Puppet::Pops::Parser::InterpolationSupport
PATTERN_VARIABLE = %r{(::)?(\w+::)*\w+}
# This is the starting point for a double quoted string with possible interpolation
# The structure mimics that of the grammar.
# The logic is explicit (where the former implementation used parameters/structures) given to a
# generic handler.
# (This is both easier to understand and faster).
#
def interpolate_dq
scn = @scanner
ctx = @lexing_context
before = scn.pos
# skip the leading " by doing a scan since the slurp_dqstring uses last matched when there is an error
scn.scan(/"/)
value,terminator = slurp_dqstring()
text = value
after = scn.pos
loop do
case terminator
when '"'
# simple case, there was no interpolation, return directly
return emit_completed([:STRING, text, scn.pos-before], before)
when '${'
count = ctx[:brace_count]
ctx[:brace_count] += 1
# The ${ terminator is counted towards the string part
enqueue_completed([:DQPRE, text, scn.pos-before], before)
# Lex expression tokens until a closing (balanced) brace count is reached
enqueue_until count
break
when '$'
varname = scn.scan(PATTERN_VARIABLE)
if varname
# The $ is counted towards the variable
enqueue_completed([:DQPRE, text, after-before-1], before)
enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
break
else
# false $ variable start
text += terminator
value,terminator = slurp_dqstring()
text += value
after = scn.pos
end
end
end
interpolate_tail_dq
# return the first enqueued token and shift the queue
@token_queue.shift
end
def interpolate_tail_dq
scn = @scanner
ctx = @lexing_context
before = scn.pos
value,terminator = slurp_dqstring
text = value
after = scn.pos
loop do
case terminator
when '"'
# simple case, there was no further interpolation, return directly
enqueue_completed([:DQPOST, text, scn.pos-before], before)
return
when '${'
count = ctx[:brace_count]
ctx[:brace_count] += 1
# The ${ terminator is counted towards the string part
enqueue_completed([:DQMID, text, scn.pos-before], before)
# Lex expression tokens until a closing (balanced) brace count is reached
enqueue_until count
break
when '$'
varname = scn.scan(PATTERN_VARIABLE)
if varname
# The $ is counted towards the variable
enqueue_completed([:DQMID, text, after-before-1], before)
enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
break
else
# false $ variable start
text += terminator
value,terminator = slurp_dqstring
text += value
after = scn.pos
end
end
end
interpolate_tail_dq
end
# This is the starting point for a un-quoted string with possible interpolation
# The logic is explicit (where the former implementation used parameters/strucures) given to a
# generic handler.
# (This is both easier to understand and faster).
#
def interpolate_uq
scn = @scanner
ctx = @lexing_context
before = scn.pos
value,terminator = slurp_uqstring()
text = value
after = scn.pos
loop do
case terminator
when ''
# simple case, there was no interpolation, return directly
enqueue_completed([:STRING, text, scn.pos-before], before)
return
when '${'
count = ctx[:brace_count]
ctx[:brace_count] += 1
# The ${ terminator is counted towards the string part
enqueue_completed([:DQPRE, text, scn.pos-before], before)
# Lex expression tokens until a closing (balanced) brace count is reached
enqueue_until count
break
when '$'
varname = scn.scan(PATTERN_VARIABLE)
if varname
# The $ is counted towards the variable
enqueue_completed([:DQPRE, text, after-before-1], before)
enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
break
else
# false $ variable start
text += terminator
value,terminator = slurp_uqstring()
text += value
after = scn.pos
end
end
end
interpolate_tail_uq
nil
end
def interpolate_tail_uq
scn = @scanner
ctx = @lexing_context
before = scn.pos
value,terminator = slurp_uqstring
text = value
after = scn.pos
loop do
case terminator
when ''
# simple case, there was no further interpolation, return directly
enqueue_completed([:DQPOST, text, scn.pos-before], before)
return
when '${'
count = ctx[:brace_count]
ctx[:brace_count] += 1
# The ${ terminator is counted towards the string part
enqueue_completed([:DQMID, text, scn.pos-before], before)
# Lex expression tokens until a closing (balanced) brace count is reached
enqueue_until count
break
when '$'
varname = scn.scan(PATTERN_VARIABLE)
if varname
# The $ is counted towards the variable
enqueue_completed([:DQMID, text, after-before-1], before)
enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
break
else
# false $ variable start
text += terminator
value,terminator = slurp_uqstring
text += value
after = scn.pos
end
end
end
interpolate_tail_uq
end
# Enqueues lexed tokens until either end of input, or the given brace_count is reached
#
def enqueue_until brace_count
scn = @scanner
ctx = @lexing_context
queue = @token_queue
queue_base = @token_queue[0]
scn.skip(self.class::PATTERN_WS)
queue_size = queue.size
until scn.eos? do
token = lex_token
if token
if token.equal?(queue_base)
# A nested #interpolate_dq call shifted the queue_base token from the @token_queue. It must
# be put back since it is intended for the top level #interpolate_dq call only.
queue.insert(0, token)
next # all relevant tokens are already on the queue
end
token_name = token[0]
ctx[:after] = token_name
if token_name == :RBRACE && ctx[:brace_count] == brace_count
qlength = queue.size - queue_size
if qlength == 1
# Single token is subject to replacement
queue[-1] = transform_to_variable(queue[-1])
elsif qlength > 1 && [:DOT, :LBRACK].include?(queue[queue_size + 1][0])
# A first word, number of name token followed by '[' or '.' is subject to replacement
# But not for other operators such as ?, +, - etc. where user must use a $ before the name
# to get a variable
queue[queue_size] = transform_to_variable(queue[queue_size])
end
return
end
queue << token
else
scn.skip(self.class::PATTERN_WS)
end
end
end
def transform_to_variable(token)
token_name = token[0]
if [:NUMBER, :NAME, :WORD].include?(token_name) || self.class::KEYWORD_NAMES[token_name] || @taskm_keywords[token_name]
t = token[1]
ta = t.token_array
[:VARIABLE, self.class::TokenValue.new([:VARIABLE, ta[1], ta[2]], t.offset, t.locator)]
else
token
end
end
# Interpolates unquoted string and transfers the result to the given lexer
# (This is used when a second lexer instance is used to lex a substring)
#
def interpolate_uq_to(lexer)
interpolate_uq
queue = @token_queue
until queue.empty? do
lexer.enqueue(queue.shift)
end
end
end
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