Parsing¶
Parsing language files in an editor is configured in the language section of an ESV file. The syntax is as follows:
language
table : $Path
start symbols : $Sorts
line comment : $String
block comment : $String * $String
fences : $Fences
For example:
language
table : target/metaborg/sdf.tbl
start symbols : File
line comment : "//"
block comment : "/*" * "*/"
fences : [ ] ( ) { }
Parse Table¶
The parse table of your language is set with the table key. By default, the parse table of an SDF specification is always produced at target/metaborg/sdf.tbl. It is only necessary to change this configuration when a custom parse table is used.
Start Symbols¶
The start symbols key determine which start symbols to use when an editor is opened. This must be a subset of the start symbols defined in the SDF3 specification of your language.
Multiple start symbols can be set with a comma-separated list:
language
start symbols : Start, Program
Comments¶
The syntax for comments is:
language
line comment : $String
block comment : $String * $String
For example, Java comments are specified as:
language
line comment : "//"
block comment : "/*" * "*/"
The line comment key determines how single-line comments are created. It is used by editors to toggle the comment for a single line. For example, in Eclipse, pressing Ctrl+/ (Cmd+/ on macOS), respectively comments or uncomments the line. The block comment key determines how multi-line comments are created. It is used when a whole block needs to be commented or uncommented. A block comment is described by the two strings denoting the start and end symbols of the block comment respectively.
Fences¶
Fences for bracket matching are set as follows:
language
fences : $Fences
The fences key determines which symbols to use and match for bracket matching. A single fence is defined by a starting and closing symbol. Multiple fences can be set with a space-separated list. Fences are used to do bracket matching in text editors.
For example, the default fences in a new Spoofax language project are:
language
fences : [ ] ( ) { }
Multi-Character Fences
Fences can contain multiple characters, but some implementations may not handle bracket matching with multiple fence characters. For example, Eclipse does not handle this case and ignores multi-character fences.
Created: October 17, 2024