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Kotlin multiplatform port of ANTLR
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/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.kotlinruntime
import com.strumenta.kotlinmultiplatform.Math
import com.strumenta.kotlinmultiplatform.arraycopy
import com.strumenta.kotlinmultiplatform.assert
import org.antlr.v4.kotlinruntime.misc.Interval
class UnbufferedTokenStream constructor(tokenSource: TokenSource, bufferSize: Int = 256) : TokenStream {
override var tokenSource: TokenSource? = null
protected set
/**
* A moving window buffer of the data being scanned. While there's a marker,
* we keep adding to buffer. Otherwise, [consume()][.consume] resets so
* we start filling at index 0 again.
*/
protected var tokens: Array
/**
* The number of tokens currently in [tokens][.tokens].
*
*
* This is not the buffer capacity, that's `tokens.length`.
*/
protected var n: Int = 0
/**
* 0..n-1 index into [tokens][.tokens] of next token.
*
*
* The `LT(1)` token is `tokens[p]`. If `p == n`, we are
* out of buffered tokens.
*/
protected var p = 0
/**
* Count up with [mark()][.mark] and down with
* [release()][.release]. When we `release()` the last mark,
* `numMarkers` reaches 0 and we reset the buffer. Copy
* `tokens[p]..tokens[n-1]` to `tokens[0]..tokens[(n-1)-p]`.
*/
protected var numMarkers = 0
/**
* This is the `LT(-1)` token for the current position.
*/
protected var lastToken: Token? = null
/**
* When `numMarkers > 0`, this is the `LT(-1)` token for the
* first token in [.tokens]. Otherwise, this is `null`.
*/
protected var lastTokenBufferStart: Token? = null
/**
* Absolute token index. It's the index of the token about to be read via
* `LT(1)`. Goes from 0 to the number of tokens in the entire stream,
* although the stream size is unknown before the end is reached.
*
*
* This value is used to set the token indexes if the stream provides tokens
* that implement [WritableToken].
*/
protected var currentTokenIndex = 0
override val text: String
get() = ""
override val sourceName: String?
get() = tokenSource!!.sourceName
protected val bufferStartIndex: Int
get() = currentTokenIndex - p
init {
this.tokenSource = tokenSource
tokens = arrayOfNulls(bufferSize)
n = 0
fill(1) // prime the pump
}
override operator fun get(i: Int): Token { // get absolute index
val bufferStartIndex = bufferStartIndex
if (i < bufferStartIndex || i >= bufferStartIndex + n) {
throw IndexOutOfBoundsException("get(" + i + ") outside buffer: " +
bufferStartIndex + ".." + (bufferStartIndex + n))
}
return tokens[i - bufferStartIndex]!!
}
override fun LT(i: Int): Token {
if (i == -1) {
return lastToken!!
}
sync(i)
val index = p + i - 1
if (index < 0) {
throw IndexOutOfBoundsException("LT($i) gives negative index")
}
if (index >= n) {
assert(n > 0 && tokens[n - 1]!!.type == Token.EOF)
return tokens[n - 1]!!
}
return tokens[index]!!
}
override fun LA(i: Int): Int {
return LT(i).type
}
override fun getText(ctx: RuleContext): String {
return getText(ctx.sourceInterval)
}
override fun getText(start: Token?, stop: Token?): String {
return getText(Interval.of(start!!.tokenIndex, stop!!.tokenIndex))
}
override fun consume() {
if (LA(1) == Token.EOF) {
throw IllegalStateException("cannot consume EOF")
}
// buf always has at least tokens[p==0] in this method due to ctor
lastToken = tokens[p] // track last token for LT(-1)
// if we're at last token and no markers, opportunity to flush buffer
if (p == n - 1 && numMarkers == 0) {
n = 0
p = -1 // p++ will leave this at 0
lastTokenBufferStart = lastToken
}
p++
currentTokenIndex++
sync(1)
}
/** Make sure we have 'need' elements from current position [p][.p]. Last valid
* `p` index is `tokens.length-1`. `p+need-1` is the tokens index 'need' elements
* ahead. If we need 1 element, `(p+1-1)==p` must be less than `tokens.length`.
*/
protected fun sync(want: Int) {
val need = p + want - 1 - n + 1 // how many more elements we need?
if (need > 0) {
fill(need)
}
}
/**
* Add `n` elements to the buffer. Returns the number of tokens
* actually added to the buffer. If the return value is less than `n`,
* then EOF was reached before `n` tokens could be added.
*/
protected fun fill(n: Int): Int {
for (i in 0 until n) {
if (this.n > 0 && tokens[this.n - 1]!!.type == Token.EOF) {
return i
}
val t = tokenSource!!.nextToken()
add(t)
}
return n
}
protected fun add(t: Token) {
if (n >= tokens.size) {
tokens = tokens.copyOf(tokens.size * 2)
}
if (t is WritableToken) {
(t as WritableToken).tokenIndex = bufferStartIndex + n
}
tokens[n++] = t
}
/**
* Return a marker that we can release later.
*
*
* The specific marker value used for this class allows for some level of
* protection against misuse where `seek()` is called on a mark or
* `release()` is called in the wrong order.
*/
override fun mark(): Int {
if (numMarkers == 0) {
lastTokenBufferStart = lastToken
}
val mark = -numMarkers - 1
numMarkers++
return mark
}
override fun release(marker: Int) {
val expectedMark = -numMarkers
if (marker != expectedMark) {
throw IllegalStateException("release() called with an invalid marker.")
}
numMarkers--
if (numMarkers == 0) { // can we release buffer?
if (p > 0) {
// Copy tokens[p]..tokens[n-1] to tokens[0]..tokens[(n-1)-p], reset ptrs
// p is last valid token; move nothing if p==n as we have no valid char
arraycopy(tokens, p, tokens, 0, n - p) // shift n-p tokens from p to 0
n = n - p
p = 0
}
lastTokenBufferStart = lastToken
}
}
override fun index(): Int {
return currentTokenIndex
}
override fun seek(index: Int) { // seek to absolute index
var index = index
if (index == currentTokenIndex) {
return
}
if (index > currentTokenIndex) {
sync(index - currentTokenIndex)
index = Math.min(index, bufferStartIndex + n - 1)
}
val bufferStartIndex = bufferStartIndex
val i = index - bufferStartIndex
if (i < 0) {
throw IllegalArgumentException("cannot seek to negative index " + index)
} else if (i >= n) {
throw UnsupportedOperationException("seek to index outside buffer: " +
index + " not in " + bufferStartIndex + ".." + (bufferStartIndex + n))
}
p = i
currentTokenIndex = index
if (p == 0) {
lastToken = lastTokenBufferStart
} else {
lastToken = tokens[p - 1]
}
}
override fun size(): Int {
throw UnsupportedOperationException("Unbuffered stream cannot know its size")
}
override fun getText(interval: Interval): String {
val bufferStartIndex = bufferStartIndex
val bufferStopIndex = bufferStartIndex + tokens.size - 1
val start = interval.a
val stop = interval.b
if (start < bufferStartIndex || stop > bufferStopIndex) {
throw UnsupportedOperationException("interval " + interval + " not in token buffer window: " +
bufferStartIndex + ".." + bufferStopIndex)
}
val a = start - bufferStartIndex
val b = stop - bufferStartIndex
val buf = StringBuilder()
for (i in a..b) {
val t = tokens[i]
buf.append(t!!.text)
}
return buf.toString()
}
}
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