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|
# frozen_string_literal: true
module TTY
class Command
# Retains the first N bytes and the last N bytes from written content
#
# @api private
class Truncator
# Default maximum byte size for prefix & suffix
DEFAULT_SIZE = 32 << 10
# Create a Truncator
#
# @param [Hash] options
# @option options [Number] max_size
#
# @api public
def initialize(options = {})
@max_size = options.fetch(:max_size) { DEFAULT_SIZE }
@prefix = ""
@suffix = ""
@skipped = 0
end
# Write content
#
# @param [String] content
# the content to write
#
# @return [nil]
#
# @api public
def write(content)
content = content.to_s.dup
content, @prefix = append(content, @prefix)
if (over = (content.bytesize - @max_size)) > 0
content = content.byteslice(over..-1)
@skipped += over
end
content, @suffix = append(content, @suffix)
# suffix is full but we still have content to write
while content.bytesize > 0
content = copy(content, @suffix)
end
end
alias << write
# Truncated representation of the content
#
# @return [String]
#
# @api public
def read
return @prefix if @suffix.empty?
if @skipped.zero?
return @prefix << @suffix
end
@prefix + "\n... omitting #{@skipped} bytes ...\n" + @suffix
end
alias to_s read
private
# Copy minimum bytes from source to destination
#
# @return [String]
# the remaining content
#
# @api private
def copy(value, dest)
bytes = value.bytesize
n = bytes < dest.bytesize ? bytes : dest.bytesize
head, tail = dest.byteslice(0...n), dest.byteslice(n..-1)
dest.replace("#{tail}#{value[0...n]}")
@skipped += head.bytesize
value.byteslice(n..-1)
end
# Append value to destination
#
# @param [String] value
#
# @param [String] dst
#
# @api private
def append(value, dst)
remain = @max_size - dst.bytesize
remaining = ""
if remain > 0
value_bytes = value.to_s.bytesize
offset = value_bytes < remain ? value_bytes : remain
remaining = value.byteslice(0...offset)
value = value.byteslice(offset..-1)
end
[value, dst + remaining]
end
end # Truncator
end # Command
end # TTY
|
