70 lines
2.3 KiB
Go
70 lines
2.3 KiB
Go
package tokenize
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import "git.makaay.nl/mauricem/go-parsekit/read"
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// ByteMode provides byte-driven input/output functionality for the tokenize API.
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type ByteMode struct {
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api *API
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reader *read.Buffer // the buffered input reader
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}
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// Peek returns the byte at the provided byte offset.
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//
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// When an error occurs during reading the input, an error will be returned.
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// When an offset is requested that is beyond the length of the available input
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// data, then the error will be io.EOF.
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func (byteMode ByteMode) Peek(offset int) (byte, error) {
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return byteMode.reader.ByteAt(byteMode.api.stackFrame.offset + offset)
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}
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func (byteMode ByteMode) Accept(b byte) {
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byteMode.api.Output.AddByte(b)
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byteMode.MoveCursor(b)
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}
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// AcceptMulti is used to accept one or more bytes that were read from the input.
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// This tells the tokenizer: "I've seen these bytes. I want to make use of them
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// for the final output, so please remember them for me. I will now continue
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// reading after these bytes."
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//
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// This will update the position of the cursor (which keeps track of what line
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// and column we are on in the input data) and add the bytes to the tokenizer
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// output.
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//
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// After the call, byte offset 0 for PeekByte() and PeekRune() will point at
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// the first byte after the accepted bytes.
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func (byteMode ByteMode) AcceptMulti(bytes ...byte) {
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byteMode.api.Output.AddBytes(bytes...)
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byteMode.MoveCursorMulti(bytes...)
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}
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// MoveCursor updates the position of the read cursor, based on the provided byte.
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// This method takes newlines into account to keep track of line numbers and
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// column positions for the input cursor.
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//
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// After the call, byte offset 0 for Peek() and PeekMulti() will point at
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// the first byte at the new cursor position.
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func (byteMode ByteMode) MoveCursor(b byte) {
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f := byteMode.api.stackFrame
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if b == '\n' {
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f.column = 0
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f.line++
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} else {
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f.column++
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}
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f.offset++
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}
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// MoveCursorMulti updates the position of the read cursor, based on the provided bytes.
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// This method takes newlines into account to keep track of line numbers and
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// column positions for the input cursor.
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//
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// After the call, byte offset 0 for Peek() and PeekMulti() will point at
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// the first byte at the new cursor position.
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func (byteMode ByteMode) MoveCursorMulti(bytes ...byte) {
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for _, b := range bytes {
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byteMode.MoveCursor(b)
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}
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}
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