elelwan

elelwan is an idea of a constructed language parseable with an LL(1) parser (hence the name).

It depends on:

• LLgen, which can be found on SlackBuilds.org,
• flex,
• gcc,
• Python 3.5,
• GNU make.

It builds upon two files: dict.txt (the dictionary) and gram.txt (the grammar). The result is an executable written to the file out.

You can build it by typing make, or try a sample input by typing make test.

The filenames can be overriden by environment variables DICT, GRAM and OUT. For example, the following command will build the executable using alternative dictionary and grammar files:

make DICT=alt-dict.txt GRAM=alt-gram.txt

(Before changing between different environments, you might want to make clean.)

dict.txt

The dictionary consists of lines of the form: word part-of-speech translation, separated by whitespace, f.i.:

ala Noun Alice
ma Verb has
kota Noun a.cat

The part of speech symbol doubles as a token name.

In order to omit the translation, leave - (a single dash).

gram.txt

The grammar consists of a header and a body, separated by %%.

The header consists of %token and %start declarations.

• %token, followed by one or more token names, declares them as part of speech names.
• %start, followed by one symbols, declares it as the starting symbol of the grammar.

Update: The %token declarations are now generated automatically. They shouldn't be included in the grammar file.

The body consists of lines of the form parent-symbol = child-symbols, where child-symbols is a list of symbols the parent can be decomposed into. Basic LLgen extensions are supported: [ ] | + * ?.

An example grammar looks as follows:

%start Sentence
%%
Sentence = NounPhrase VerbPhrase
NounPhrase = Noun
VerbPhrase = Verb Noun

out

The output executable works as follows: for a given input, it decomposes it into words and then parses it according to the grammar, outputting a syntax tree in bracketed form.

For instance, for the input of ala ma kota, the aforementioned grammar should output:

[Sentence
  [NounPhrase
    [Noun ala  # Alice]
  ]
  [VerbPhrase
    [Verb ma  # has]
    [Noun kota  # a.cat]
  ]
]

(The output can be later converted into an image using e.g. Miles Shang's syntree or Yoichiro Hasebe's RSyntaxTree.)