/**

* Provides classes and predicates related to jump-to-definition links

* in the code viewer.

*/

import csharp

import IDEContextual

/** An element with an associated definition. */

abstract class Use extends @type_mention_parent {

/**

* Holds if this element is at the specified location.

* The location spans column `startcolumn` of line `startline` to

* column `endcolumn` of line `endline` in file `filepath`.

* For more information, see

* [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).

*/

predicate hasLocationInfo(

string filepath, int startline, int startcolumn, int endline, int endcolumn

) {

exists(Location l |

l = this.(Element).getLocation() or

l = this.(TypeMention).getLocation()

|

filepath = l.getFile().getAbsolutePath() and

startline = l.getStartLine() and

startcolumn = l.getStartColumn() and

endline = l.getEndLine() and

endcolumn = l.getEndColumn()

)

}

/** Gets the definition associated with this element. */

abstract Declaration getDefinition();

/**

* Gets the type of use.

*

* - `"M"`: call.

* - `"V"`: variable use.

* - `"T"`: type reference.

*/

abstract string getUseType();

/** Gets a textual representation of this element. */

abstract string toString();

}

/** A method call/access. */

private class MethodUse extends Use, QualifiableExpr {

MethodUse() {

this instanceof MethodCall or

this instanceof MethodAccess

}

/** Gets the qualifier of this method use, if any. */

private Expr getFormatQualifier() {

(

if this.getQualifiedDeclaration().(Method).isExtensionMethod()

then result = this.(MethodCall).getArgument(0)

else result = this.getQualifier()

) and

not result.isImplicit()

}

override predicate hasLocationInfo(

string filepath, int startline, int startcolumn, int endline, int endcolumn

) {

Use.super.hasLocationInfo(filepath, _, _, _, _) and

endline = startline and

endcolumn = startcolumn + this.getQualifiedDeclaration().getName().length() - 1 and

(

exists(Location ql | ql = this.getFormatQualifier().getLocation() |

startline = ql.getEndLine() and

startcolumn = ql.getEndColumn() + 2

)

or

not exists(this.getFormatQualifier()) and

exists(Location l | l = this.getLocation() |

startline = l.getStartLine() and

startcolumn = l.getStartColumn()

)

)

}

override Method getDefinition() {

result = this.getQualifiedDeclaration().getUnboundDeclaration()

}

override string getUseType() { result = "M" }

override string toString() { result = this.(Expr).toString() }

}

/** An access. */

private class AccessUse extends Access, Use {

AccessUse() {

not this.getTarget().(Parameter).getCallable() instanceof Accessor and

not this = any(LocalVariableDeclAndInitExpr d).getLValue() and

not this.isImplicit() and

not this instanceof MethodAccess and // handled by `MethodUse`

not this instanceof TypeAccess and // handled by `TypeMentionUse`

not this.(FieldAccess).getParent() instanceof Field and // Enum initializer

not this.(FieldAccess).getParent().getParent() instanceof Field and // Field initializer

not this.(PropertyAccess).getParent().getParent() instanceof Property // Property initializer

}

/** Gets the qualifier of this access, if any. */

private Expr getFormatQualifier() {

result = this.(QualifiableExpr).getQualifier() and

not result.isImplicit()

}

override predicate hasLocationInfo(

string filepath, int startline, int startcolumn, int endline, int endcolumn

) {

exists(Location ql | ql = this.getFormatQualifier().getLocation() |

startline = ql.getEndLine() and

startcolumn = ql.getEndColumn() + 2 and

Use.super.hasLocationInfo(filepath, _, _, endline, endcolumn)

)

or

not exists(this.getFormatQualifier()) and

Use.super.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)

}

override Declaration getDefinition() { result = this.getTarget().getUnboundDeclaration() }

override string getUseType() {

if this instanceof Call or this instanceof LocalFunctionAccess

then result = "M"

else

if this instanceof BaseAccess or this instanceof ThisAccess

then result = "T"

else result = "V"

}

override string toString() { result = this.(Access).toString() }

}

/** A type mention. */

private class TypeMentionUse extends Use, TypeMention {

TypeMentionUse() {

// In type mentions such as `T[]`, `T?`, `T*`, and `(S, T)`, we only want

// uses for the nested type mentions

forall(TypeMention child, Type t |

child.getParent() = this and

t = this.getType()

|

not t instanceof ArrayType and

not t instanceof NullableType and

not t instanceof PointerType and

not t instanceof TupleType

)

}

override predicate hasLocationInfo(

string filepath, int startline, int startcolumn, int endline, int endcolumn

) {

Use.super.hasLocationInfo(filepath, startline, startcolumn, endline, _) and

endcolumn =

startcolumn +

this.getType().(ConstructedType).getUnboundGeneric().getUndecoratedName().length() - 1

or

Use.super.hasLocationInfo(filepath, startline, startcolumn, endline, _) and

endcolumn = startcolumn + this.getType().(UnboundGenericType).getUndecoratedName().length() - 1

or

not this.getType() instanceof ConstructedType and

not this.getType() instanceof UnboundGenericType and

Use.super.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)

}

override Type getDefinition() { result = this.getType().getUnboundDeclaration() }

override string getUseType() {

if this.getTarget() instanceof ObjectCreation

then result = "M" // constructor call

else result = "T"

}

override string toString() { result = TypeMention.super.toString() }

}

/**

* Gets an element, of kind `kind`, that element `e` uses, if any.

*/

cached

Declaration definitionOf(Use use, string kind) {

result = use.getDefinition() and

result.fromSource() and

kind = use.getUseType() and

// Some entities have many locations. This can arise for files that

// are duplicated multiple times in the database at different

// locations. Rather than letting the result set explode, we just

// exclude results that are "too ambiguous" -- we could also arbitrarily

// pick one location later on.

strictcount(result.getLocation()) < 10

}