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module state.definition;
import std.string;
import std.variant;
import std.typecons;
import std.container : DList;
import state.stack;
alias Words = Stack!Token[string];
Words words;
bool handle(Token token) {
return token.visit!(
(int value) => handle(value),
(bool value) => handle(value),
(string word ) => handle(word)
);
}
Stack!Token get(string word) {
if ( word in words ) {
return words[word].dup;
} else {
return Stack!Token(Token(word));
}
}
private {
Nullable!(DList!Token) definition;
void register(DList!Token definition) {
string wordToBeDefined;
definition.front.visit!(
(int value) => wordToBeDefined = "",
(bool value) => wordToBeDefined = "",
(string name ) => wordToBeDefined = name
);
if ( wordToBeDefined == "" ) {
throw new Exception("words may not be numeric or boolean");
}
definition.removeFront;
words[wordToBeDefined] = Stack!Token(definition[]);
}
template handle(T)
if ( is(T == int) || is(T == bool) ) {
bool handle(T value) {
if ( definition.isNull ) {
return false;
} else {
definition.insertBack(Token(value));
return true;
}
}
}
bool handle(string word) {
if ( definition.isNull ) {
if ( word == "§" ) {
definition = DList!Token();
return true;
} else {
return false;
}
} else {
switch ( word ) {
case "§" :
throw new Exception("definitions may not be nested");
case ";" :
register(definition);
definition.nullify;
break;
default:
definition.insertBack(Token(word));
}
return true;
}
}
}
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