Metasyntax and BNF Grammar

Navigate this page:

• Metasyntax
  
• Nonterminal Symbols
• Terminal Symbols
• BNF Grammar

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Metasyntax

A metasyntax is defined by nonterminal symbols and terminal symbols.

Nonterminal Symbols

• START - Necessary to define the beginning of our semantic;
• TITLE - Title of the song;
• AUTHOR - Author of the song (field not mandatory);
• BAR - Beat expressed in quarters (x/4);
• SOUND - Every possible sound that defines a song, can by any of the following:
• NOTE - Single note;
• CHORD - Simply a chord;
• POWERCHORD - Definition of Power Chord;
• STRUMMING - Definition of Strumming;
• SLIDEUP - Definition of Slide Up;
• SLIDEDOWN - Definition of Slide Down;
• HAMMER - Definition of Hammer-On;
• PULLOFF - Definition of Pull-Off;
• PAUSE_G - A graphical pause;
• NEWLINE - Produces a line break.

Terminal Symbols

The terminal symbols we'll use are:

• Numbers from 1 to 4 for defining the beat;
• Numbers from 1 to 24 for defining the frets;
• Numbers from 1 to 6 for defining strings;
• Characters from 'A' to 'G' for defining notes;
• Words pause and pause_g for defining the normal pause and the graphical pause;
• Word newline in order to start a new line;
• All the words from the dictionary for defining Author and title of the song;
• Some useful symbols suchs as '(' ')' ','.

BNF Grammar

START	→	OUT
S	→	START
START	→	TITLE
TITLE	→	'(' WORD ')'AUTHOR
TITLE	→	'(' WORD ')'BAR
AUTHOR	→	'(' WORD ')'BAR
BAR	→	'(' A '/' A ')' SOUND
SOUND	→	SOUND
SOUND	→	NOTE
NOTE	→	'(' T ',' F ')'
SOUND	→	CHORD
CHORD	→	'(' C ')'
SOUND	→	POWERCHORD
POWERCHORD	→	'(' T ',' F ')'
SOUND	→	STRUMMING
STRUMMING	→	'(' F ',' F ',' F ',' F ',' F ',' F ')'
SOUND	→	SLIDEUP
SLIDEUP	→	'(' C ',' F ',' F ')'
SOUND	→	SLIDEDOWN
SLIDEDOWN	→	'(' C ',' F ',' F ')'
SOUND	→	HAMMER
HAMMER	→	'(' C ',' F ',' F ')'
SOUND	→	PULLOFF
PULLOFF	→	'(' C ',' F ',' F ')'
SOUND	→	PAUSE
PAUSE	→	'pause'
SOUND	→	PAUSE_G
SOUND	→	'pause_g'
SOUND	→	NEWLINE
NEWLINE	->	'newline'
A (beAt)	→	1..4
F (Fret)	→	1..24
T (sTring)	→	1..6
C (Chord)	→	'A'..'G'
WORD	→	All the vocabulary

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