Expression

All Known Implementing Classes:

CelExpr
```
@Internal
public interface Expression
```
An abstract representation of a common expression.
Expressions are abstractly represented as a collection of identifiers, select statements, function calls, literals, and comprehensions. All operators with the exception of the '.' operator are modelled as function calls. This makes it easy to represent new operators into the existing AST.
All references within expressions must resolve to a [Decl][] provided at type-check for an expression to be valid. A reference may either be a bare identifier `name` or a qualified identifier `google.api.name`. References may either refer to a value or a function declaration.
For example, the expression `google.api.name.startsWith('expr')` references the declaration `google.api.name` within a [Expr.Select][] expression, and the function declaration `startsWith`.

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static interface`	`Expression.Call<E extends Expression>`	A call expression, including calls to predefined functions and operators.
`static interface`	`Expression.Comprehension<E extends Expression>`	A comprehension expression applied to a list or map.
`static interface`	`Expression.Ident`	An identifier expression.
`static interface`	`Expression.List<E extends Expression>`	A list creation expression.
`static interface`	`Expression.Map<E extends Expression.Map.Entry<?>>`	A map creation expression.
`static interface`	`Expression.Select<E extends Expression>`	A field selection expression.
`static interface`	`Expression.Struct<E extends Expression.Struct.Entry<?>>`	A message creation expression.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`<E extends Expression> Expression.Call<E>`	`call()`	Gets the underlying call expression.
`<E extends Expression> Expression.Comprehension<E>`	`comprehension()`	Gets the underlying comprehension expression.
`CelConstant`	`constant()`	Gets the underlying constant expression.
`CelExpr.ExprKind.Kind`	`getKind()`	Represents the enumeration value for the underlying expression kind.
`long`	`id()`	Required.
`Expression.Ident`	`ident()`	Gets the underlying identifier expression.
`<E extends Expression> Expression.List<E>`	`list()`	Gets the underlying identifier expression.
`<E extends Expression> Expression.Map<Expression.Map.Entry<E>>`	`map()`	Gets the underlying map expression.
`<E extends Expression> Expression.Select<E>`	`select()`	Gets the underlying select expression.
`<E extends Expression> Expression.Struct<Expression.Struct.Entry<E>>`	`struct()`	Gets the underlying struct expression.

- Method Detail
  - id
```
long id()
```
    Required. An id assigned to this node by the parser which is unique in a given expression tree. This is used to associate type information and other attributes to a node in the parse tree.
  - getKind
```
CelExpr.ExprKind.Kind getKind()
```
    Represents the enumeration value for the underlying expression kind.
  - constant
```
CelConstant constant()
```
    Gets the underlying constant expression.
  - ident
```
Expression.Ident ident()
```
    Gets the underlying identifier expression.
  - call
```
<E extends Expression> Expression.Call<E> call()
```
    Gets the underlying call expression.
  - list
```
<E extends Expression> Expression.List<E> list()
```
    Gets the underlying identifier expression.
  - select
```
<E extends Expression> Expression.Select<E> select()
```
    Gets the underlying select expression.
  - struct
```
<E extends Expression> Expression.Struct<Expression.Struct.Entry<E>> struct()
```
    Gets the underlying struct expression.
  - map
```
<E extends Expression> Expression.Map<Expression.Map.Entry<E>> map()
```
    Gets the underlying map expression.
  - comprehension
```
<E extends Expression> Expression.Comprehension<E> comprehension()
```
    Gets the underlying comprehension expression.