# GH_Lexer class

Namespace: [Grasshopper.Kernel.Data](https://developer.rhino3d.com/api/gh1/namespace/grasshopper.kernel.data.md) · Assembly: [Grasshopper](https://developer.rhino3d.com/api/gh1/assembly/grasshopper.md)

```cs
public class GH_Lexer
```

Represents a lexical mask for path operations.

## Constructors

- [GH_Lexer](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/ctor.md): (2 overloads) Blank constructor.

## Properties

- [IsItem](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/isitem.md): Gets a value indicating whether or not the item portion of the lexer has been set.
- [IsPath](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/ispath.md): Gets a value indicating whether or not the path portion of the lexer has been set.
- [Item](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/item.md): Gets the item string that was extracted from the mask. The default is "append"
- [Mask](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/mask.md): Gets the original string that represents the user input for this lexer.
- [Path](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/path.md): Gets the list of path strings that was extracted from the mask. If the mask hasn't been parsed yet, it will be parsed now. If the returned list is still nothing, parsing failed.

## Methods

- [EvaluatePath](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/evaluatepath.md): Evaluate the variables in this mask with the provided expression solver.
- [PerformLexicalReplace<T>](https://developer.rhino3d.com/api/gh1/type/grasshopper.kernel.data.gh-lexer/performlexicalreplace.md): (2 overloads, static) Lexical Find..Replace operations.