syntax

package
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 Go to latest Published: Nov 1, 2018 License: BSD-3-Clause Imports: 10 Imported by: 9

Documentation

Overview

Package syntax provides a Skylark parser and abstract syntax tree.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Walk 

func Walk(n Node, f func(Node) bool)

Walk traverses a syntax tree in depth-first order. It starts by calling f(n); n must not be nil. If f returns true, Walk calls itself recursively for each non-nil child of n. Walk then calls f(nil).

Types

type AssignStmt 

type AssignStmt struct {
	OpPos Position
	Op    Token // = EQ | {PLUS,MINUS,STAR,PERCENT}_EQ
	LHS   Expr
	RHS   Expr
	// contains filtered or unexported fields
}

An AssignStmt represents an assignment: 

x = 0
x, y = y, x
x += 1

func (*AssignStmt) AllocComments 

func (cr *AssignStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (AssignStmt) Comments 

func (cr AssignStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*AssignStmt) Span 

func (x *AssignStmt) Span() (start, end Position)

type BinaryExpr 

type BinaryExpr struct {
	X     Expr
	OpPos Position
	Op    Token
	Y     Expr
	// contains filtered or unexported fields
}

A BinaryExpr represents a binary expression: X Op Y.

func (*BinaryExpr) AllocComments 

func (cr *BinaryExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (BinaryExpr) Comments 

func (cr BinaryExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*BinaryExpr) Span 

func (x *BinaryExpr) Span() (start, end Position)

type BranchStmt 

type BranchStmt struct {
	Token    Token // = BREAK | CONTINUE | PASS
	TokenPos Position
	// contains filtered or unexported fields
}

A BranchStmt changes the flow of control: break, continue, pass.

func (*BranchStmt) AllocComments 

func (cr *BranchStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (BranchStmt) Comments 

func (cr BranchStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*BranchStmt) Span 

func (x *BranchStmt) Span() (start, end Position)

type CallExpr 

type CallExpr struct {
	Fn     Expr
	Lparen Position
	Args   []Expr // arg = expr | ident=expr | *expr | **expr
	Rparen Position
	// contains filtered or unexported fields
}

A CallExpr represents a function call expression: Fn(Args).

func (*CallExpr) AllocComments 

func (cr *CallExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (CallExpr) Comments 

func (cr CallExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*CallExpr) Span 

func (x *CallExpr) Span() (start, end Position)

type Comment 

type Comment struct {
	Start Position
	Text  string // without trailing newline
}

A Comment represents a single # comment.

type Comments 

type Comments struct {
	Before []Comment // whole-line comments before this expression
	Suffix []Comment // end-of-line comments after this expression (up to 1)

	// For top-level expressions only, After lists whole-line
	// comments following the expression.
	After []Comment
}

Comments collects the comments associated with an expression.

type Comprehension 

type Comprehension struct {
	Curly   bool // {x:y for ...} or {x for ...}, not [x for ...]
	Lbrack  Position
	Body    Expr
	Clauses []Node // = *ForClause | *IfClause
	Rbrack  Position
	// contains filtered or unexported fields
}

A Comprehension represents a list or dict comprehension: [Body for ... if ...] or {Body for ... if ...}

func (*Comprehension) AllocComments 

func (cr *Comprehension) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (Comprehension) Comments 

func (cr Comprehension) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*Comprehension) Span 

func (x *Comprehension) Span() (start, end Position)

type CondExpr 

type CondExpr struct {
	If      Position
	Cond    Expr
	True    Expr
	ElsePos Position
	False   Expr
	// contains filtered or unexported fields
}

CondExpr represents the conditional: X if COND else ELSE.

func (*CondExpr) AllocComments 

func (cr *CondExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (CondExpr) Comments 

func (cr CondExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*CondExpr) Span 

func (x *CondExpr) Span() (start, end Position)

type DefStmt 

type DefStmt struct {
	Def  Position
	Name *Ident
	Function
	// contains filtered or unexported fields
}

A DefStmt represents a function definition.

func (*DefStmt) AllocComments 

func (cr *DefStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (DefStmt) Comments 

func (cr DefStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*DefStmt) Span 

func (x *DefStmt) Span() (start, end Position)

type DictEntry 

type DictEntry struct {
	Key   Expr
	Colon Position
	Value Expr
	// contains filtered or unexported fields
}

A DictEntry represents a dictionary entry: Key: Value. Used only within a DictExpr.

func (*DictEntry) AllocComments 

func (cr *DictEntry) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (DictEntry) Comments 

func (cr DictEntry) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*DictEntry) Span 

func (x *DictEntry) Span() (start, end Position)

type DictExpr 

type DictExpr struct {
	Lbrace Position
	List   []Expr // all *DictEntrys
	Rbrace Position
	// contains filtered or unexported fields
}

A DictExpr represents a dictionary literal: { List }.

func (*DictExpr) AllocComments 

func (cr *DictExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (DictExpr) Comments 

func (cr DictExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*DictExpr) Span 

func (x *DictExpr) Span() (start, end Position)

type DotExpr 

type DotExpr struct {
	X       Expr
	Dot     Position
	NamePos Position
	Name    *Ident
	// contains filtered or unexported fields
}

A DotExpr represents a field or method selector: X.Name.

func (*DotExpr) AllocComments 

func (cr *DotExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (DotExpr) Comments 

func (cr DotExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*DotExpr) Span 

func (x *DotExpr) Span() (start, end Position)

type Error 

type Error struct {
	Pos Position
	Msg string
}

An Error describes the nature and position of a scanner or parser error.

func (Error) Error 

func (e Error) Error() string

type Expr 

type Expr interface {
	Node
	// contains filtered or unexported methods
}

An Expr is a Skylark expression.

func ParseExpr 

func ParseExpr(filename string, src interface{}, mode Mode) (expr Expr, err error)

ParseExpr parses a Skylark expression. See Parse for explanation of parameters.

type ExprStmt 

type ExprStmt struct {
	X Expr
	// contains filtered or unexported fields
}

An ExprStmt is an expression evaluated for side effects.

func (*ExprStmt) AllocComments 

func (cr *ExprStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ExprStmt) Comments 

func (cr ExprStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ExprStmt) Span 

func (x *ExprStmt) Span() (start, end Position)

type File 

type File struct {
	Path  string
	Stmts []Stmt

	// set by resolver:
	Locals  []*Ident // this file's (comprehension-)local variables
	Globals []*Ident // this file's global variables
	// contains filtered or unexported fields
}

A File represents a Skylark file.

func Parse 

func Parse(filename string, src interface{}, mode Mode) (f *File, err error)

Parse parses the input data and returns the corresponding parse tree.

If src != nil, ParseFile parses the source from src and the filename is only used when recording position information. The type of the argument for the src parameter must be string, []byte, or io.Reader. If src == nil, ParseFile parses the file specified by filename.

func (*File) AllocComments 

func (cr *File) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (File) Comments 

func (cr File) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*File) Span 

func (x *File) Span() (start, end Position)

type ForClause 

type ForClause struct {
	For  Position
	Vars Expr // name, or tuple of names
	In   Position
	X    Expr
	// contains filtered or unexported fields
}

A ForClause represents a for clause in a list comprehension: for Vars in X.

func (*ForClause) AllocComments 

func (cr *ForClause) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ForClause) Comments 

func (cr ForClause) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ForClause) Span 

func (x *ForClause) Span() (start, end Position)

type ForStmt 

type ForStmt struct {
	For  Position
	Vars Expr // name, or tuple of names
	X    Expr
	Body []Stmt
	// contains filtered or unexported fields
}

A ForStmt represents a loop: for Vars in X: Body.

func (*ForStmt) AllocComments 

func (cr *ForStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ForStmt) Comments 

func (cr ForStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ForStmt) Span 

func (x *ForStmt) Span() (start, end Position)

type Function 

type Function struct {
	StartPos Position // position of DEF or LAMBDA token
	Params   []Expr   // param = ident | ident=expr | *ident | **ident
	Body     []Stmt

	// set by resolver:
	HasVarargs bool     // whether params includes *args (convenience)
	HasKwargs  bool     // whether params includes **kwargs (convenience)
	Locals     []*Ident // this function's local variables, parameters first
	FreeVars   []*Ident // enclosing local variables to capture in closure
	// contains filtered or unexported fields
}

A Function represents the common parts of LambdaExpr and DefStmt.

func (*Function) AllocComments 

func (cr *Function) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (Function) Comments 

func (cr Function) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*Function) Span 

func (x *Function) Span() (start, end Position)

type Ident 

type Ident struct {
	NamePos Position
	Name    string

	Scope uint8 // see type resolve.Scope
	Index int   // index into enclosing {DefStmt,File}.Locals (if scope==Local) or DefStmt.FreeVars (if scope==Free) or File.Globals (if scope==Global)
	// contains filtered or unexported fields
}

An Ident represents an identifier.

func (*Ident) AllocComments 

func (cr *Ident) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (Ident) Comments 

func (cr Ident) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*Ident) Span 

func (x *Ident) Span() (start, end Position)

type IfClause 

type IfClause struct {
	If   Position
	Cond Expr
	// contains filtered or unexported fields
}

An IfClause represents an if clause in a list comprehension: if Cond.

func (*IfClause) AllocComments 

func (cr *IfClause) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (IfClause) Comments 

func (cr IfClause) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*IfClause) Span 

func (x *IfClause) Span() (start, end Position)

type IfStmt 

type IfStmt struct {
	If      Position // IF or ELIF
	Cond    Expr
	True    []Stmt
	ElsePos Position // ELSE or ELIF
	False   []Stmt   // optional
	// contains filtered or unexported fields
}

An IfStmt is a conditional: If Cond: True; else: False. 'elseif' is desugared into a chain of IfStmts.

func (*IfStmt) AllocComments 

func (cr *IfStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (IfStmt) Comments 

func (cr IfStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*IfStmt) Span 

func (x *IfStmt) Span() (start, end Position)

type IndexExpr 

type IndexExpr struct {
	X      Expr
	Lbrack Position
	Y      Expr
	Rbrack Position
	// contains filtered or unexported fields
}

An IndexExpr represents an index expression: X[Y].

func (*IndexExpr) AllocComments 

func (cr *IndexExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (IndexExpr) Comments 

func (cr IndexExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*IndexExpr) Span 

func (x *IndexExpr) Span() (start, end Position)

type LambdaExpr 

type LambdaExpr struct {
	Lambda Position
	Function
	// contains filtered or unexported fields
}

A LambdaExpr represents an inline function abstraction.

Although they may be added in future, lambda expressions are not currently part of the Skylark spec, so their use is controlled by the resolver.AllowLambda flag.

func (*LambdaExpr) AllocComments 

func (cr *LambdaExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (LambdaExpr) Comments 

func (cr LambdaExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*LambdaExpr) Span 

func (x *LambdaExpr) Span() (start, end Position)

type ListExpr 

type ListExpr struct {
	Lbrack Position
	List   []Expr
	Rbrack Position
	// contains filtered or unexported fields
}

A ListExpr represents a list literal: [ List ].

func (*ListExpr) AllocComments 

func (cr *ListExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ListExpr) Comments 

func (cr ListExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ListExpr) Span 

func (x *ListExpr) Span() (start, end Position)

type Literal 

type Literal struct {
	Token    Token // = STRING | INT
	TokenPos Position
	Raw      string      // uninterpreted text
	Value    interface{} // = string | int64 | *big.Int
	// contains filtered or unexported fields
}

A Literal represents a literal string or number.

func (*Literal) AllocComments 

func (cr *Literal) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (Literal) Comments 

func (cr Literal) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*Literal) Span 

func (x *Literal) Span() (start, end Position)

type LoadStmt 

type LoadStmt struct {
	Load   Position
	Module *Literal // a string
	From   []*Ident // name defined in loading module
	To     []*Ident // name in loaded module
	Rparen Position
	// contains filtered or unexported fields
}

A LoadStmt loads another module and binds names from it: load(Module, "x", y="foo").

The AST is slightly unfaithful to the concrete syntax here because Skylark's load statement, so that it can be implemented in Python, binds some names (like y above) with an identifier and some (like x) without. For consistency we create fake identifiers for all the strings.

func (*LoadStmt) AllocComments 

func (cr *LoadStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (LoadStmt) Comments 

func (cr LoadStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*LoadStmt) ModuleName 

func (x *LoadStmt) ModuleName() string

ModuleName returns the name of the module loaded by this statement.

func (*LoadStmt) Span 

func (x *LoadStmt) Span() (start, end Position)

type Mode 

type Mode uint

A Mode value is a set of flags (or 0) that controls optional parser functionality. 

const (
	RetainComments Mode = 1 << iota // retain comments in AST; see Node.Comments
)

type Node 

type Node interface {
	// Span returns the start and end position of the expression.
	Span() (start, end Position)

	// Comments returns the comments associated with this node.
	// It returns nil if RetainComments was not specified during parsing,
	// or if AllocComments was not called.
	Comments() *Comments

	// AllocComments allocates a new Comments node if there was none.
	// This makes possible to add new comments using Comments() method.
	AllocComments()
}

A Node is a node in a Skylark syntax tree.

type ParenExpr 

type ParenExpr struct {
	Lparen Position
	X      Expr
	Rparen Position
	// contains filtered or unexported fields
}

A ParenExpr represents a parenthesized expression: (X).

func (*ParenExpr) AllocComments 

func (cr *ParenExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ParenExpr) Comments 

func (cr ParenExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ParenExpr) Span 

func (x *ParenExpr) Span() (start, end Position)

type Position 

type Position struct {
	Line int32 // 1-based line number
	Col  int32 // 1-based column number (strictly: rune)
	// contains filtered or unexported fields
}

A Position describes the location of a rune of input.

func End 

func End(n Node) Position

End returns the end position of the expression.

func MakePosition 

func MakePosition(file *string, line, col int32) Position

MakePosition returns position with the specified components.

func Start 

func Start(n Node) Position

Start returns the start position of the expression.

func (Position) Filename 

func (p Position) Filename() string

Filename returns the name of the file containing this position.

func (Position) IsValid 

func (p Position) IsValid() bool

IsValid reports whether the position is valid.

func (Position) String 

func (p Position) String() string

type ReturnStmt 

type ReturnStmt struct {
	Return Position
	Result Expr // may be nil
	// contains filtered or unexported fields
}

A ReturnStmt returns from a function.

func (*ReturnStmt) AllocComments 

func (cr *ReturnStmt) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (ReturnStmt) Comments 

func (cr ReturnStmt) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*ReturnStmt) Span 

func (x *ReturnStmt) Span() (start, end Position)

type SliceExpr 

type SliceExpr struct {
	X            Expr
	Lbrack       Position
	Lo, Hi, Step Expr // all optional
	Rbrack       Position
	// contains filtered or unexported fields
}

A SliceExpr represents a slice or substring expression: X[Lo:Hi:Step].

func (*SliceExpr) AllocComments 

func (cr *SliceExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (SliceExpr) Comments 

func (cr SliceExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*SliceExpr) Span 

func (x *SliceExpr) Span() (start, end Position)

type Stmt 

type Stmt interface {
	Node
	// contains filtered or unexported methods
}

A Stmt is a Skylark statement.

type Token 

type Token int8

A Token represents a Skylark lexical token. 

const (
	ILLEGAL Token = iota
	EOF

	NEWLINE
	INDENT
	OUTDENT

	// Tokens with values
	IDENT  // x
	INT    // 123
	FLOAT  // 1.23e45
	STRING // "foo" or 'foo' or ”'foo”' or r'foo' or r"foo"

	// Punctuation
	PLUS          // +
	MINUS         // -
	STAR          // *
	SLASH         // /
	SLASHSLASH    // //
	PERCENT       // %
	AMP           // &
	PIPE          // |
	CIRCUMFLEX    // ^
	LTLT          // <<
	GTGT          // >>
	TILDE         // ~
	DOT           // .
	COMMA         // ,
	EQ            // =
	SEMI          // ;
	COLON         // :
	LPAREN        // (
	RPAREN        // )
	LBRACK        // [
	RBRACK        // ]
	LBRACE        // {
	RBRACE        // }
	LT            // <
	GT            // >
	GE            // >=
	LE            // <=
	EQL           // ==
	NEQ           // !=
	PLUS_EQ       // +=    (keep order consistent with PLUS..GTGT)
	MINUS_EQ      // -=
	STAR_EQ       // *=
	SLASH_EQ      // /=
	SLASHSLASH_EQ // //=
	PERCENT_EQ    // %=
	AMP_EQ        // &=
	PIPE_EQ       // |=
	CIRCUMFLEX_EQ // ^=
	LTLT_EQ       // <<=
	GTGT_EQ       // >>=
	STARSTAR      // **

	// Keywords
	AND
	BREAK
	CONTINUE
	DEF
	ELIF
	ELSE
	FOR
	IF
	IN
	LAMBDA
	LOAD
	NOT
	NOT_IN // synthesized by parser from NOT IN
	OR
	PASS
	RETURN
)

func (Token) GoString 

func (tok Token) GoString() string

GoString is like String but quotes punctuation tokens. Use Sprintf("%#v", tok) when constructing error messages.

func (Token) String 

func (tok Token) String() string

type TupleExpr 

type TupleExpr struct {
	Lparen Position // optional (e.g. in x, y = 0, 1), but required if List is empty
	List   []Expr
	Rparen Position
	// contains filtered or unexported fields
}

A TupleExpr represents a tuple literal: (List).

func (*TupleExpr) AllocComments 

func (cr *TupleExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (TupleExpr) Comments 

func (cr TupleExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*TupleExpr) Span 

func (x *TupleExpr) Span() (start, end Position)

type UnaryExpr 

type UnaryExpr struct {
	OpPos Position
	Op    Token
	X     Expr
	// contains filtered or unexported fields
}

A UnaryExpr represents a unary expression: Op X.

func (*UnaryExpr) AllocComments 

func (cr *UnaryExpr) AllocComments()

AllocComments enables comments to be associated with a syntax node.

func (UnaryExpr) Comments 

func (cr UnaryExpr) Comments() *Comments

Comments returns the comments associated with a syntax node, or nil if AllocComments has not yet been called.

func (*UnaryExpr) Span 

func (x *UnaryExpr) Span() (start, end Position)

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