Class: HeadMusic::Notation::ABC::Preflight

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/notation/abc/preflight.rb

Overview

Boundary checks the Parser runs before it interprets a tune, so a caller never receives a reference to a partially built composition. Each check raises on the first problem it finds and is otherwise a no-op. They run at distinct points of construction — blank input before the header is read, trailing content once the header exists, unsupported tokens after lexing — so each takes exactly the input it inspects rather than sharing state.

Class Method Summary collapse

Class Method Details

.ensure_input_present(abc_string) ⇒ Object

Raises:



10
11
12
13
14
 
# File 'lib/head_music/notation/abc/preflight.rb', line 10

def self.ensure_input_present(abc_string)
  return unless abc_string.to_s.strip.empty?

  raise ParseError, "ABC input is blank"
end

.reject_content_after_tune(header) ⇒ Object

The lexer treats a blank line as the end of the tune, so anything after it would be silently dropped — most likely another tune.

Raises:



18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
 
# File 'lib/head_music/notation/abc/preflight.rb', line 18

def self.reject_content_after_tune(header)
  lines = header.body.lines
  blank_index = lines.find_index { |line| line.strip.empty? }
  return unless blank_index

  extra_lines = lines[(blank_index + 1)..]
  extra_index = extra_lines.find_index do |line|
    stripped = line.strip
    !stripped.empty? && !stripped.start_with?("%")
  end
  return unless extra_index

  raise ParseError.new(
    "Content after the tune body; parse a book of tunes with ABC.parse_book",
    line_number: header.body_start_line + blank_index + 1 + extra_index,
    snippet: extra_lines[extra_index].strip[0, BodyLexer::SNIPPET_LENGTH]
  )
end

.reject_unsupported_tokens(tokens) ⇒ Object

Raises:



37
38
39
40
41
42
43
44
45
46
 
# File 'lib/head_music/notation/abc/preflight.rb', line 37

def self.reject_unsupported_tokens(tokens)
  token = tokens.find { |candidate| candidate.type == :unsupported }
  return unless token

  lexeme = token.lexeme
  raise UnsupportedFeatureError.new(
    "Unsupported ABC feature #{lexeme.inspect}",
    line_number: token.line, snippet: lexeme
  )
end