syntax

Documentation

Index

• Variables
• func IsExtendedGraphic(r rune) bool
• type Lexer
  • func NewLexer(input *bufio.Reader, charConversions map[rune]rune) *Lexer
  • func (l *Lexer) Next() (Token, error)
• type Token
  • func (t Token) String() string
• type TokenKind
  • func (k TokenKind) String() string
• type UnexpectedRuneError
  • func (e UnexpectedRuneError) Error() string

Variables

var ErrInsufficient = errors.New("insufficient input")

ErrInsufficient represents an error which is raised when the given input is insufficient for a term.

var Spacing = [tokenKindLen][tokenKindLen]bool{
	TokenVariable: {
		TokenVariable: true,
		TokenInteger:  true,
		TokenFloat:    true,
		TokenIdent:    true,
	},
	TokenIdent: {
		TokenVariable: true,
		TokenInteger:  true,
		TokenFloat:    true,
		TokenIdent:    true,
	},
	TokenGraphic: {
		TokenGraphic: true,
		TokenSign:    true,
	},
	TokenComma: {
		TokenVariable:    true,
		TokenFloat:       true,
		TokenInteger:     true,
		TokenIdent:       true,
		TokenQuotedIdent: true,
		TokenGraphic:     true,
		TokenComma:       true,
		TokenPeriod:      true,
		TokenBar:         true,
		TokenParenL:      true,
		TokenParenR:      true,
		TokenBracketL:    true,
		TokenBracketR:    true,
		TokenBraceL:      true,
		TokenBraceR:      true,
		TokenSign:        true,
	},
	TokenSign: {
		TokenGraphic: true,
	},
}

Spacing describes which token kinds require spaces between them.

Functions

func IsExtendedGraphic

func IsExtendedGraphic(r rune) bool

IsExtendedGraphic checks if the rune is a graphic token, comma, or semicolon.

Types

type Lexer

type Lexer struct {
	// contains filtered or unexported fields
}

Lexer turns bytes into tokens.

func NewLexer

func NewLexer(input *bufio.Reader, charConversions map[rune]rune) *Lexer

NewLexer create a lexer with an input and char conversions.

func (*Lexer) Next

func (l *Lexer) Next() (Token, error)

Next returns the next token.

type Token

type Token struct {
	Kind TokenKind
	Val  string
}

Token is a smallest meaningful unit of prolog program.

func (Token) String

func (t Token) String() string

type TokenKind

type TokenKind byte

TokenKind is a type of Token.

const (
	// TokenEOS represents an end of token stream.
	TokenEOS TokenKind = iota

	// TokenVariable represents a variable token.
	TokenVariable

	// TokenFloat represents a floating-point token.
	TokenFloat

	// TokenInteger represents an integer token.
	TokenInteger

	// TokenIdent represents an identifier token.
	TokenIdent

	// TokenQuotedIdent represents a quoted identifier token.
	TokenQuotedIdent

	// TokenGraphic represents a graphical token.
	TokenGraphic

	// TokenComma represents a comma.
	TokenComma

	// TokenPeriod represents a period.
	TokenPeriod

	// TokenBar represents a bar.
	TokenBar

	// TokenParenL represents an open parenthesis.
	TokenParenL

	// TokenParenR represents a close parenthesis.
	TokenParenR

	// TokenBracketL represents an open bracket.
	TokenBracketL

	// TokenBracketR represents a close bracket.
	TokenBracketR

	// TokenBraceL represents an open brace.
	TokenBraceL

	// TokenBraceR represents a close brace.
	TokenBraceR

	// TokenSign represents a plus/minus.
	TokenSign

	// TokenDoubleQuoted represents a double-quoted string.
	TokenDoubleQuoted
)

func (TokenKind) String

func (k TokenKind) String() string

type UnexpectedRuneError

type UnexpectedRuneError struct {
	// contains filtered or unexported fields
}

UnexpectedRuneError represents an error which is raised when the given input contains an unexpected rune.

func (UnexpectedRuneError) Error

func (e UnexpectedRuneError) Error() string