Documentation
¶
Overview ¶
Package token defines the lexical elements of a River config and utilities surrounding their position.
Index ¶
Constants ¶
const (
LowestPrecedence = 0 // non-operators
UnaryPrecedence = 7
HighestPrecedence = 8
)
Levels of precedence for operator tokens.
Variables ¶
var NoPos = Pos{}
NoPos is the zero value for Pos. It has no file or line information associated with it, and NoPos.Valid is false.
Functions ¶
This section is empty.
Types ¶
type File ¶
type File struct {
// contains filtered or unexported fields
}
File holds position information for a specific file.
func NewFile ¶
func NewFile(filename string) *File
NewFile creates a new File for storing position information.
func (*File) AddLine ¶
func (f *File) AddLine(offset int)
AddLine tracks a new line from a byte offset. The line offset must be larger than the offset for the previous line, otherwise the line offset is ignored.
func (*File) Pos ¶
func (f *File) Pos(off int) Pos
Pos returns a Pos given a byte offset. Pos panics if off is < 0.
func (*File) PositionFor ¶
func (f *File) PositionFor(p Pos) Position
PositionFor returns a Position from an offset.
type Pos ¶
type Pos struct {
// contains filtered or unexported fields
}
Pos is a compact representation of a position within a file. It can be converted into a Position for a more convenient, but larger, representation.
func (Pos) File ¶
func (p Pos) File() *File
File returns the file used by the Pos. This will be nil for invalid positions.
type Position ¶
type Position struct {
Filename string // Filename (if any)
Offset int // Byte offset (starting at 0)
Line int // Line number (starting at 1)
Column int // Offset from start of line (starting at 1)
}
Position holds full position information for a location within an individual file.
func (Position) String ¶
func (pos Position) String() string
String returns a string in one of the following forms:
file:line:column Valid position with file name file:line Valid position with file name but no column line:column Valid position with no file name line Valid position with no file name or column file Invalid position with file name - Invalid position with no file name
type Token ¶
type Token int
Token is an individual River lexical token.
const (
ILLEGAL Token = iota // Invalid token.
LITERAL // Literal text.
EOF // End-of-file.
COMMENT // // Hello, world!
IDENT // foobar
NUMBER // 1234
FLOAT // 1234.0
STRING // "foobar"
BOOL // true
NULL // null
OR // ||
AND // &&
NOT // !
ASSIGN // =
EQ // ==
NEQ // !=
LT // <
LTE // <=
GT // >
GTE // >=
ADD // +
SUB // -
MUL // *
DIV // /
MOD // %
POW // ^
LCURLY // {
RCURLY // }
LPAREN // (
RPAREN // )
LBRACK // [
RBRACK // ]
COMMA // ,
DOT // .
TERMINATOR // \n
)
List of all lexical tokens and examples that represent them.
LITERAL is used by token/builder to represent literal strings for writing tokens, but never used for reading (so scanner never returns a token.LITERAL).
func Lookup ¶
func Lookup(ident string) Token
Lookup maps a string to its keyword token or IDENT if it's not a keyword.
func (Token) BinaryPrecedence ¶
func (t Token) BinaryPrecedence() int
BinaryPrecedence returns the operator precedence of the binary operator t. If t is not a binary operator, the result is LowestPrecedence.
func (Token) IsKeyword ¶
func (t Token) IsKeyword() bool
IsKeyword returns true if the token corresponds to a keyword.
func (Token) IsLiteral ¶
func (t Token) IsLiteral() bool
IsLiteral returns true if the token corresponds to a literal token or identifier.
func (Token) IsOperator ¶
func (t Token) IsOperator() bool
IsOperator returns true if the token corresponds to an operator or delimiter.
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