public void Completion_Grammar_TypicalExpression()
{
// arrange
var expression = "var c = a + b";
var inputStream = new AntlrInputStream(expression);
var lexer = new ExprLexer(inputStream);
var tokenStream = new CommonTokenStream(lexer);
var parser = new ExprParser(tokenStream);
parser.Interpreter.PredictionMode = PredictionMode.LlExactAmbigDetection;
lexer.RemoveErrorListeners();
parser.RemoveErrorListeners();
var errorListener = new CountingErrorListener();
parser.AddErrorListener(errorListener);
// act
// assert
// Specify our entry point
var tree = parser.expression();
Check.That(errorListener.ErrorCount).IsEqualTo(0);
// Tell the engine to return certain rules to us, which we could use to look up values in a symbol table.
var preferredRules = new HashSet <int>()
{
ExprParser.RULE_functionRef, ExprParser.RULE_variableRef
};
// Ignore operators and the generic ID token.
var ignoredTokens = new HashSet <int>()
{
ExprLexer.PLUS, ExprLexer.MINUS,
ExprLexer.MULTIPLY, ExprLexer.DIVIDE
};
var core = new CodeCompletionCore(parser, preferredRules, ignoredTokens);
// 1) At the input start.
var candidates = core.CollectCandidates(0, null);
Check.That(candidates.Tokens).HasSize(2);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.VAR);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.LET);
Check.That(candidates.Tokens
.TryGetValue(ExprLexer.VAR, out var varCandidates))
.IsTrue();
Check.That(candidates.Tokens
.TryGetValue(ExprLexer.LET, out var letCandidates))
.IsTrue();
Check.That(varCandidates).HasSize(2);
Check.That(letCandidates).HasSize(2);
Check.That(varCandidates).IsEqualTo(new[] { ExprLexer.ID, ExprLexer.EQUAL });
Check.That(letCandidates).IsEqualTo(new[] { ExprLexer.ID, ExprLexer.EQUAL });
// 2) On the variable name ('c').
ignoredTokens = new HashSet <int>()
{
ExprLexer.ID, ExprLexer.PLUS, ExprLexer.MINUS,
ExprLexer.MULTIPLY, ExprLexer.DIVIDE, ExprLexer.EQUAL
};
core = new CodeCompletionCore(parser, preferredRules, ignoredTokens);
candidates = core.CollectCandidates(2, null);
Check.That(candidates.Tokens).HasSize(0);
// 4) On the equal sign (ignoring whitespace positions from now on).
candidates = core.CollectCandidates(4, null);
Check.That(candidates.Tokens).HasSize(0);
// 5) On the variable reference 'a'.
candidates = core.CollectCandidates(6, null);
Check.That(candidates.Tokens).HasSize(0);
Check.That(candidates.Rules).HasSize(2);
// Here we get 2 rule indexes, derived from 2 different IDs possible at this caret position.
// These are what we told the engine above to be preferred rules for us.
var found = 0;
foreach (var candidate in candidates.Rules)
{
switch (candidate.Key)
{
case ExprParser.RULE_functionRef:
{
found++;
break;
}
case ExprParser.RULE_variableRef:
{
found++;
break;
}
}
}
Check.That(found).Equals(2);
// 6) On the whitespace after the 'a'
candidates = core.CollectCandidates(7, null);
Check.That(candidates.Tokens).HasSize(0);
Check.That(candidates.Rules).HasSize(1);
// Here we get 2 rule indexes
found = 0;
foreach (var candidate in candidates.Rules)
{
switch (candidate.Key)
{
case ExprParser.RULE_functionRef:
{
found++;
break;
}
case ExprParser.RULE_variableRef:
{
found++;
break;
}
}
}
Check.That(found).Equals(1);
}
public void Completion_Grammar_SimpleExpression()
{
// arrange
var input = "var c = a + b()";
var inputStream = new AntlrInputStream(input);
var lexer = new ExprLexer(inputStream);
var tokenStream = new CommonTokenStream(lexer);
var parser = new ExprParser(tokenStream);
lexer.RemoveErrorListeners();
parser.RemoveErrorListeners();
var errorListener = new CountingErrorListener();
parser.AddErrorListener(errorListener);
// act
// assert
// Specify our entry point
var tree = parser.expression();
Check.That(errorListener.ErrorCount).IsEqualTo(0);
var core = new CodeCompletionCore(parser, null, null);
// 1) At the input start.
var candidates = core.CollectCandidates(0, null);
Check.That(candidates.Tokens).HasSize(3);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.VAR);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.LET);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.ID);
Check.That(candidates.Tokens[ExprLexer.VAR]).IsEqualTo(new[] { ExprLexer.ID, ExprLexer.EQUAL });
Check.That(candidates.Tokens[ExprLexer.LET]).IsEqualTo(new[] { ExprLexer.ID, ExprLexer.EQUAL });
Check.That(candidates.Tokens[ExprLexer.ID]).HasSize(0);
// 2) On the first whitespace. In real implementations you would do some additional checks where in the whitespace
// the caret is, as the outcome is different depending on that position.
candidates = core.CollectCandidates(1, null);
Check.That(candidates.Tokens).HasSize(1);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.ID);
// 3) On the variable name ('c').
candidates = core.CollectCandidates(2, null);
Check.That(candidates.Tokens).HasSize(1);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.ID);
// 4) On the equal sign (ignoring whitespace positions from now on).
candidates = core.CollectCandidates(4, null);
Check.That(candidates.Tokens).HasSize(1);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.EQUAL);
// 5) On the variable reference 'a'. But since we have not configure the c3 engine to return us var refs
// (or function refs for that matter) we only get an ID here.
candidates = core.CollectCandidates(6, null);
Check.That(candidates.Tokens).HasSize(1);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.ID);
// 6) On the '+' operator. Usually you would not show operators as candidates, but we have not set up the c3 engine
// yet to not return them.
candidates = core.CollectCandidates(8, null);
Check.That(candidates.Tokens).HasSize(5);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.PLUS);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.MINUS);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.MULTIPLY);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.DIVIDE);
Check.That(candidates.Tokens).ContainsKey(ExprLexer.OPEN_PAR);
}