102 lines
2.7 KiB
Go
102 lines
2.7 KiB
Go
package parsekit
|
|
|
|
import (
|
|
"fmt"
|
|
"strings"
|
|
)
|
|
|
|
// ItemType represents the type of a parser Item.
|
|
type ItemType int
|
|
|
|
// TODO private?
|
|
// ItemEOF is a built-in parser item type that is used for flagging that the
|
|
// end of the input was reached.
|
|
const ItemEOF ItemType = -1
|
|
|
|
// TODO private?
|
|
// ItemError is a built-in parser item type that is used for flagging that
|
|
// an error has occurred during parsing.
|
|
const ItemError ItemType = -2
|
|
|
|
// Item represents an item that can be emitted from the parser.
|
|
type Item struct {
|
|
Type ItemType
|
|
Value string
|
|
}
|
|
|
|
// Emit passes a Parser item to the client, including the provided string.
|
|
func (p *P) Emit(t ItemType, s string) {
|
|
p.items <- Item{t, s}
|
|
p.buffer.reset()
|
|
}
|
|
|
|
// EmitLiteral passes a Parser item to the client, including accumulated
|
|
// string buffer data as a literal string.
|
|
func (p *P) EmitLiteral(t ItemType) {
|
|
p.Emit(t, p.buffer.asLiteralString())
|
|
}
|
|
|
|
// EmitLiteralTrim passes a Parser item to the client, including
|
|
// accumulated string buffer data as a literal string with whitespace
|
|
// trimmed from it.
|
|
func (p *P) EmitLiteralTrim(t ItemType) {
|
|
p.Emit(t, strings.TrimSpace(p.buffer.asLiteralString()))
|
|
}
|
|
|
|
// EmitInterpreted passes a Parser item to the client, including
|
|
// accumulated string buffer data a Go doubled quoted interpreted string
|
|
// (handling escape codes like \n, \t, \uXXXX, etc.)
|
|
// This method might return an error, in case there is data in the
|
|
// string buffer that is not valid for string interpretation.
|
|
func (p *P) EmitInterpreted(t ItemType) error {
|
|
s, err := p.buffer.asInterpretedString()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
p.Emit(t, s)
|
|
return nil
|
|
}
|
|
|
|
// Error is used as the error type when parsing errors occur.
|
|
// The error includes some extra meta information to allow for useful
|
|
// error messages to the user.
|
|
type Error struct {
|
|
Message string
|
|
Row int
|
|
Column int
|
|
}
|
|
|
|
func (err *Error) Error() string {
|
|
return err.Message
|
|
}
|
|
|
|
// EmitError emits a Parser error item to the client.
|
|
func (p *P) EmitError(format string, args ...interface{}) {
|
|
message := fmt.Sprintf(format, args...)
|
|
p.Emit(ItemError, message)
|
|
}
|
|
|
|
// UnexpectedInput is used by a parser implementation to emit an
|
|
// error item that tells the client that an unexpected rune was
|
|
// encountered in the input.
|
|
func (p *P) UnexpectedInput() {
|
|
r, _, ok := p.peek(0)
|
|
switch {
|
|
case ok:
|
|
p.EmitError("unexpected character %q%s", r, fmtExpects(p))
|
|
case r == EOF:
|
|
p.EmitError("unexpected end of file%s", fmtExpects(p))
|
|
case r == INVALID:
|
|
p.EmitError("invalid UTF8 character in input%s", fmtExpects(p))
|
|
default:
|
|
panic("Unhandled output from peek()")
|
|
}
|
|
}
|
|
|
|
func fmtExpects(p *P) string {
|
|
if p.expecting == "" {
|
|
return ""
|
|
}
|
|
return fmt.Sprintf(" (expected %s)", p.expecting)
|
|
}
|