import "cuelang.org/go/cue/ast"
Package ast declares the types used to represent syntax trees for CUE packages.
ast.go comments.go ident.go walk.go
ErrIsExpression reports whether a label is an expression. This error is never returned directly. Use errors.Is or xerrors.Is.
func AddComment(n Node, cg *CommentGroup)
AddComment adds the given comment to the node if it supports it. If a node does not support comments, such as for CommentGroup or Comment, this call has no effect.
Embed can be used in conjunction with NewStruct to embed values.
IsValidIdent reports whether str is a valid identifier.
LabelName reports the name of a label, whether it is an identifier (it binds a value to a scope), and whether it is valid. Keywords that are allowed in label positions are interpreted accordingly.
Examples:
Label Result foo "foo" true nil true "true" true nil "foo" "foo" false nil "x-y" "x-y" false nil "foo "" false invalid string "\(x)" "" false errors.Is(err, ErrIsExpression) X=foo "foo" true nil
Name describes the type of n.
ParseIdent unquotes a possibly quoted identifier and validates if the result is valid.
Deprecated: quoted identifiers are deprecated. Use aliases.
QuoteIdent quotes an identifier, if needed, and reports an error if the identifier is invalid.
Deprecated: quoted identifiers are deprecated. Use aliases.
func SetComments(n Node, cgs []*CommentGroup)
SetComments replaces all comments of n with the given set of comments. If a node does not support comments, such as for CommentGroup or Comment, this call has no effect.
SetPos sets a node to the given position, if possible.
SetRelPos sets the relative position of a node without modifying its file position. Setting it to token.NoRelPos allows a node to adopt default formatting.
Walk traverses an AST in depth-first order: It starts by calling f(node); node must not be nil. If before returns true, Walk invokes f recursively for each of the non-nil children of node, followed by a call of after. Both functions may be nil. If before is nil, it is assumed to always return true.
type Alias struct {
Ident *Ident // field name, always an Ident
Equal token.Pos // position of "="
Expr Expr // An Ident or SelectorExpr
// contains filtered or unexported fields
}An Alias binds another field to the alias name in the current struct.
func (c *Alias) AddComment(cg *CommentGroup)
func (c *Alias) Comments() []*CommentGroup
func (c *Alias) SetComments(cgs []*CommentGroup)
type Attribute struct {
At token.Pos
Text string // must be a valid attribute format.
// contains filtered or unexported fields
}An Attribute provides meta data about a field.
func (c *Attribute) AddComment(cg *CommentGroup)
func (c *Attribute) Comments() []*CommentGroup
func (c *Attribute) SetComments(cgs []*CommentGroup)
type BadDecl struct {
From, To token.Pos // position range of bad declaration
// contains filtered or unexported fields
}A BadDecl node is a placeholder for declarations containing syntax errors for which no correct declaration nodes can be created.
func (c *BadDecl) AddComment(cg *CommentGroup)
func (c *BadDecl) Comments() []*CommentGroup
func (c *BadDecl) SetComments(cgs []*CommentGroup)
type BadExpr struct {
From, To token.Pos // position range of bad expression
// contains filtered or unexported fields
}A BadExpr node is a placeholder for expressions containing syntax errors for which no correct expression nodes can be created. This is different from an ErrorExpr which represents an explicitly marked error in the source.
func (c *BadExpr) AddComment(cg *CommentGroup)
func (c *BadExpr) Comments() []*CommentGroup
func (c *BadExpr) SetComments(cgs []*CommentGroup)
type BasicLit struct {
ValuePos token.Pos // literal position
Kind token.Token // INT, FLOAT, DURATION, or STRING
Value string // literal string; e.g. 42, 0x7f, 3.14, 1_234_567, 1e-9, 2.4i, 'a', '\x7f', "foo", or '\m\n\o'
// contains filtered or unexported fields
}A BasicLit node represents a literal of basic type.
NewBool creates a new BasicLit with a bool value without position. Useful for ASTs generated by code other than the CUE parser.
NewLit creates a new BasicLit with from a token type and string without position. Useful for ASTs generated by code other than the CUE parser.
NewNull creates a new BasicLit configured to be a null value. Useful for ASTs generated by code other than the CUE parser.
NewString creates a new BasicLit with a string value without position. It quotes the given string. Useful for ASTs generated by code other than the CUE parser.
func (c *BasicLit) AddComment(cg *CommentGroup)
func (c *BasicLit) Comments() []*CommentGroup
func (c *BasicLit) SetComments(cgs []*CommentGroup)
type BinaryExpr struct {
X Expr // left operand
OpPos token.Pos // position of Op
Op token.Token // operator
Y Expr // right operand
// contains filtered or unexported fields
}A BinaryExpr node represents a binary expression.
func (c *BinaryExpr) AddComment(cg *CommentGroup)
func (c *BinaryExpr) Comments() []*CommentGroup
func (x *BinaryExpr) End() token.Pos
func (x *BinaryExpr) Pos() token.Pos
func (c *BinaryExpr) SetComments(cgs []*CommentGroup)
A BottomLit indicates an error.
func (c *BottomLit) AddComment(cg *CommentGroup)
func (c *BottomLit) Comments() []*CommentGroup
func (c *BottomLit) SetComments(cgs []*CommentGroup)
type CallExpr struct {
Fun Expr // function expression
Lparen token.Pos // position of "("
Args []Expr // function arguments; or nil
Rparen token.Pos // position of ")"
// contains filtered or unexported fields
}A CallExpr node represents an expression followed by an argument list.
NewCall creates a new CallExpr. Useful for ASTs generated by code other than the CUE parser.
func (c *CallExpr) AddComment(cg *CommentGroup)
func (c *CallExpr) Comments() []*CommentGroup
func (c *CallExpr) SetComments(cgs []*CommentGroup)
Clause nodes are part of comprehensions.
type Comment struct {
Slash token.Pos // position of "/" starting the comment
Text string // comment text (excluding '\n' for //-style comments)
}A Comment node represents a single //-style or /*-style comment.
func (c *Comment) AddComment(*CommentGroup)
func (c *Comment) Comments() []*CommentGroup
type CommentGroup struct {
// TODO: remove and use the token position of the first comment.
Doc bool
Line bool // true if it is on the same line as the node's end pos.
// Position indicates where a comment should be attached if a node has
// multiple tokens. 0 means before the first token, 1 means before the
// second, etc. For instance, for a field, the positions are:
// <0> Label <1> ":" <2> Expr <3> "," <4>
Position int8
List []*Comment // len(List) > 0
// contains filtered or unexported fields
}A CommentGroup represents a sequence of comments with no other tokens and no empty lines between.
func Comments(n Node) []*CommentGroup
Comments returns all comments associated with a given node.
func (g *CommentGroup) AddComment(*CommentGroup)
func (g *CommentGroup) Comments() []*CommentGroup
func (g *CommentGroup) End() token.Pos
func (g *CommentGroup) Pos() token.Pos
func (g *CommentGroup) Text() string
Text returns the text of the comment. Comment markers (//, /*, and */), the first space of a line comment, and leading and trailing empty lines are removed. Multiple empty lines are reduced to one, and trailing space on lines is trimmed. Unless the result is empty, it is newline-terminated.
type Comprehension struct {
Clauses []Clause // There must be at least one clause.
Value Expr // Must be a struct TODO: change to Struct
// contains filtered or unexported fields
}A Comprehension node represents a comprehension declaration.
func (c *Comprehension) AddComment(cg *CommentGroup)
func (c *Comprehension) Comments() []*CommentGroup
func (x *Comprehension) End() token.Pos
func (x *Comprehension) Pos() token.Pos
func (c *Comprehension) SetComments(cgs []*CommentGroup)
A Decl node is implemented by all declarations.
type Ellipsis struct {
Ellipsis token.Pos // open list if set
Type Expr // type for the remaining elements
// contains filtered or unexported fields
}func (c *Ellipsis) AddComment(cg *CommentGroup)
func (c *Ellipsis) Comments() []*CommentGroup
func (c *Ellipsis) SetComments(cgs []*CommentGroup)
An EmbedDecl node represents a single expression used as a declaration. The expressions in this declaration is what will be emitted as configuration output.
An EmbedDecl may only appear at the top level.
func (c *EmbedDecl) AddComment(cg *CommentGroup)
func (c *EmbedDecl) Comments() []*CommentGroup
func (c *EmbedDecl) SetComments(cgs []*CommentGroup)
An Expr is implemented by all expression nodes.
NewBinExpr creates for list of expressions of length 2 or greater a chained binary expression of the form (((x1 op x2) op x3) ...). For lists of length 1 it returns the expression itself. It panics for empty lists. Useful for ASTs generated by code other than the CUE parser.
NewSel creates a sequence of selectors. Useful for ASTs generated by code other than the CUE parser.
type Field struct {
Label Label // must have at least one element.
Optional token.Pos
// No TokenPos: Value must be an StructLit with one field.
TokenPos token.Pos
Token token.Token // ':' or '::', ILLEGAL implies ':'
Value Expr // the value associated with this field.
Attrs []*Attribute
// contains filtered or unexported fields
}A Field represents a field declaration in a struct.
func (c *Field) AddComment(cg *CommentGroup)
func (c *Field) Comments() []*CommentGroup
func (c *Field) SetComments(cgs []*CommentGroup)
type File struct {
Filename string
Decls []Decl // top-level declarations; or nil
Imports []*ImportSpec // imports in this file
Unresolved []*Ident // unresolved identifiers in this file
// contains filtered or unexported fields
}A File node represents a Go source file.
The Comments list contains all comments in the source file in order of appearance, including the comments that are pointed to from other nodes via Doc and Comment fields.
func (c *File) AddComment(cg *CommentGroup)
func (c *File) Comments() []*CommentGroup
PackageName returns the package name associated with this file or "" if no package is associated.
Preamble returns the declarations of the preamble.
func (c *File) SetComments(cgs []*CommentGroup)
func (f *File) VisitImports(fn func(d *ImportDecl))
type ForClause struct {
For token.Pos
Key *Ident // allow pattern matching?
// TODO: change to Comma
Colon token.Pos
Value *Ident // allow pattern matching?
In token.Pos
Source Expr
// contains filtered or unexported fields
}A ForClause node represents a for clause in a comprehension.
func (c *ForClause) AddComment(cg *CommentGroup)
func (c *ForClause) Comments() []*CommentGroup
func (c *ForClause) SetComments(cgs []*CommentGroup)
type Ident struct {
NamePos token.Pos // identifier position
// This LHS path element may be an identifier. Possible forms:
// foo: a normal identifier
// "foo": JSON compatible
// <foo>: a template shorthand
Name string
Scope Node // scope in which node was found or nil if referring directly
Node Node
// contains filtered or unexported fields
}An Ident node represents an left-hand side identifier.
NewIdent creates a new Ident without position. Useful for ASTs generated by code other than the CUE parser.
func (c *Ident) AddComment(cg *CommentGroup)
func (c *Ident) Comments() []*CommentGroup
func (c *Ident) SetComments(cgs []*CommentGroup)
A IfClause node represents an if guard clause in a comprehension.
func (c *IfClause) AddComment(cg *CommentGroup)
func (c *IfClause) Comments() []*CommentGroup
func (c *IfClause) SetComments(cgs []*CommentGroup)
type ImportDecl struct {
Import token.Pos
Lparen token.Pos // position of '(', if any
Specs []*ImportSpec
Rparen token.Pos // position of ')', if any
// contains filtered or unexported fields
}A ImportDecl node represents a series of import declarations. A valid Lparen position (Lparen.Line > 0) indicates a parenthesized declaration.
func (c *ImportDecl) AddComment(cg *CommentGroup)
func (c *ImportDecl) Comments() []*CommentGroup
func (d *ImportDecl) End() token.Pos
func (d *ImportDecl) Pos() token.Pos
func (c *ImportDecl) SetComments(cgs []*CommentGroup)
type ImportSpec struct {
Name *Ident // local package name (including "."); or nil
Path *BasicLit // import path
EndPos token.Pos // end of spec (overrides Path.Pos if nonzero)
// contains filtered or unexported fields
}An ImportSpec node represents a single package import.
func NewImport(name *Ident, importPath string) *ImportSpec
func (c *ImportSpec) AddComment(cg *CommentGroup)
func (c *ImportSpec) Comments() []*CommentGroup
func (s *ImportSpec) End() token.Pos
func (s *ImportSpec) Pos() token.Pos
func (c *ImportSpec) SetComments(cgs []*CommentGroup)
type IndexExpr struct {
X Expr // expression
Lbrack token.Pos // position of "["
Index Expr // index expression
Rbrack token.Pos // position of "]"
// contains filtered or unexported fields
}An IndexExpr node represents an expression followed by an index.
func (c *IndexExpr) AddComment(cg *CommentGroup)
func (c *IndexExpr) Comments() []*CommentGroup
func (c *IndexExpr) SetComments(cgs []*CommentGroup)
type Interpolation struct {
Elts []Expr // interleaving of strings and expressions.
// contains filtered or unexported fields
}A Interpolation node represents a string or bytes interpolation.
func (c *Interpolation) AddComment(cg *CommentGroup)
func (c *Interpolation) Comments() []*CommentGroup
func (x *Interpolation) End() token.Pos
func (x *Interpolation) Pos() token.Pos
func (c *Interpolation) SetComments(cgs []*CommentGroup)
A Label is any production that can be used as a LHS label.
type LetClause struct {
Let token.Pos
Ident *Ident
Equal token.Pos
Expr Expr
// contains filtered or unexported fields
}A LetClause node represents a let clause in a comprehension.
func (c *LetClause) AddComment(cg *CommentGroup)
func (c *LetClause) Comments() []*CommentGroup
func (c *LetClause) SetComments(cgs []*CommentGroup)
type ListComprehension struct {
Lbrack token.Pos // position of "["
Expr Expr
Clauses []Clause // Feed or Guard (TODO let)
Rbrack token.Pos // position of "]"
// contains filtered or unexported fields
}A ListComprehension node represents as list comprehension.
func (c *ListComprehension) AddComment(cg *CommentGroup)
func (c *ListComprehension) Comments() []*CommentGroup
func (x *ListComprehension) End() token.Pos
func (x *ListComprehension) Pos() token.Pos
func (c *ListComprehension) SetComments(cgs []*CommentGroup)
type ListLit struct {
Lbrack token.Pos // position of "["
// TODO: change to embedding or similar.
Elts []Expr // list of composite elements; or nil
Rbrack token.Pos // position of "]"
// contains filtered or unexported fields
}A ListLit node represents a literal list.
NewList creates a list of Expressions. Useful for ASTs generated by code other than the CUE parser.
func (c *ListLit) AddComment(cg *CommentGroup)
func (c *ListLit) Comments() []*CommentGroup
func (c *ListLit) SetComments(cgs []*CommentGroup)
type Node interface {
Pos() token.Pos // position of first character belonging to the node
End() token.Pos // position of first character immediately after the node
// Deprecated: use ast.Comments
Comments() []*CommentGroup
// Deprecated: use ast.AddComment
AddComment(*CommentGroup)
// contains filtered or unexported methods
}A Node represents any node in the abstract syntax tree.
type Package struct {
PackagePos token.Pos // position of "package" pseudo-keyword
Name *Ident // package name
// contains filtered or unexported fields
}A Package represents a package clause.
func (c *Package) AddComment(cg *CommentGroup)
func (c *Package) Comments() []*CommentGroup
func (c *Package) SetComments(cgs []*CommentGroup)
type ParenExpr struct {
Lparen token.Pos // position of "("
X Expr // parenthesized expression
Rparen token.Pos // position of ")"
// contains filtered or unexported fields
}A ParenExpr node represents a parenthesized expression.
func (c *ParenExpr) AddComment(cg *CommentGroup)
func (c *ParenExpr) Comments() []*CommentGroup
func (c *ParenExpr) SetComments(cgs []*CommentGroup)
type SelectorExpr struct {
X Expr // expression
Sel Label // field selector
// contains filtered or unexported fields
}A SelectorExpr node represents an expression followed by a selector.
func (c *SelectorExpr) AddComment(cg *CommentGroup)
func (c *SelectorExpr) Comments() []*CommentGroup
func (x *SelectorExpr) End() token.Pos
func (x *SelectorExpr) Pos() token.Pos
func (c *SelectorExpr) SetComments(cgs []*CommentGroup)
type SliceExpr struct {
X Expr // expression
Lbrack token.Pos // position of "["
Low Expr // begin of slice range; or nil
High Expr // end of slice range; or nil
Rbrack token.Pos // position of "]"
// contains filtered or unexported fields
}An SliceExpr node represents an expression followed by slice indices.
func (c *SliceExpr) AddComment(cg *CommentGroup)
func (c *SliceExpr) Comments() []*CommentGroup
func (c *SliceExpr) SetComments(cgs []*CommentGroup)
type StructLit struct {
Lbrace token.Pos // position of "{"
Elts []Decl // list of elements; or nil
Rbrace token.Pos // position of "}"
// contains filtered or unexported fields
}A StructLit node represents a literal struct.
NewStruct creates a struct from the given fields.
A field is either a *Field, an *Elipsis, *LetClause, a *CommentGroup, or a Label, optionally followed by a a token.OPTION to indicate the field is optional, optionally followed by a token.ISA to indicate the field is a definition followed by an expression for the field value.
It will panic if a values not matching these patterns are given. Useful for ASTs generated by code other than the CUE parser.
func (c *StructLit) AddComment(cg *CommentGroup)
func (c *StructLit) Comments() []*CommentGroup
func (c *StructLit) SetComments(cgs []*CommentGroup)
type TemplateLabel struct {
Langle token.Pos
Ident *Ident
Rangle token.Pos
// contains filtered or unexported fields
}A TemplateLabel represents a field template declaration in a struct.
Deprecated: use square bracket notation through ListLit.
func (c *TemplateLabel) AddComment(cg *CommentGroup)
func (c *TemplateLabel) Comments() []*CommentGroup
func (x *TemplateLabel) End() token.Pos
func (x *TemplateLabel) Pos() token.Pos
func (c *TemplateLabel) SetComments(cgs []*CommentGroup)
type UnaryExpr struct {
OpPos token.Pos // position of Op
Op token.Token // operator
X Expr // operand
// contains filtered or unexported fields
}A UnaryExpr node represents a unary expression.
func (c *UnaryExpr) AddComment(cg *CommentGroup)
func (c *UnaryExpr) Comments() []*CommentGroup
func (c *UnaryExpr) SetComments(cgs []*CommentGroup)
| Path | Synopsis |
|---|---|
| astutil |
Package ast imports 8 packages (graph) and is imported by 47 packages. Updated 2021-01-23. Refresh now. Tools for package owners.