Barebones of int selfie (#23)

selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Literals.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2023 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.selfie
+
+class LiteralValue<T : Any>(val expected: T?, val actual: T, val format: LiteralFormat<T>) {
+  fun encodedActual(): String = format.encode(actual)
+}
+
+interface LiteralFormat<T : Any> {
+  fun encode(value: T): String
+  fun parse(str: String): T
+}
+
+class IntFormat : LiteralFormat<Int> {
+  override fun encode(value: Int): String {
+    // TODO: 1000000 is hard to read, 1_000_000 is much much better
+    return value.toString()
+  }
+  override fun parse(str: String): Int {
+    return str.replace("_", "").toInt()
+  }
+}
+
+class StrFormat : LiteralFormat<String> {
+  override fun encode(value: String): String {
+    if (!value.contains("\n")) {
+      // TODO: replace \t, maybe others...
+      return "\"" + value.replace("\"", "\\\"") + "\""
+    } else {
+      // TODO: test! It's okay to assume Java 15+ for now
+      return "\"\"\"\n" + value + "\"\"\""
+    }
+  }
+  override fun parse(str: String): String {
+    TODO("Harder than it seems!")
+  }
+}

selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Slice.kt

@@ -15,34 +15,18 @@
  */
 package com.diffplug.selfie
 
-import kotlin.jvm.JvmStatic
-import kotlin.math.min
-
-/**
- * A [CharSequence] which can efficiently subdivide and append itself.
- *
- * Equal only to other [Slice] with the same [Slice.toString]. Use [Slice.sameAs] to compare with
- * other kinds of [CharSequence].
- */
-internal expect fun groupImpl(slice: Slice, matchResult: MatchResult, group: Int): Slice
-
-class Slice private constructor(val base: CharSequence, val startIndex: Int, val endIndex: Int) :
+internal class Slice(val base: String, val startIndex: Int = 0, val endIndex: Int = base.length) :
     CharSequence {
   init {
-    require(base is StringBuilder || base is String)
     require(0 <= startIndex)
     require(startIndex <= endIndex)
     require(endIndex <= base.length)
   }
   override val length: Int
     get() = endIndex - startIndex
   override fun get(index: Int): Char = base[startIndex + index]
-  override fun subSequence(start: Int, end: Int): Slice {
-    return Slice(base, startIndex + start, startIndex + end)
-  }
-
-  /** Returns a Slice representing the given group within the given match */
-  fun group(matchResult: MatchResult, group: Int): Slice = groupImpl(this, matchResult, group)
+  override fun subSequence(start: Int, end: Int): Slice =
+      Slice(base, startIndex + start, startIndex + end)
 
   /** Same behavior as [String.trim]. */
   fun trim(): Slice {
@@ -57,89 +41,6 @@ class Slice private constructor(val base: CharSequence, val startIndex: Int, val
     return if (start > 0 || end < length) subSequence(start, end) else this
   }
   override fun toString() = base.subSequence(startIndex, endIndex).toString()
-  fun concat(other: Slice): Slice =
-      if (this.isEmpty()) {
-        other
-      } else if (other.isEmpty()) {
-        this
-      } else if (base === other.base && endIndex == other.startIndex) {
-        Slice(base, startIndex, other.endIndex)
-      } else {
-        val builder: StringBuilder
-        val start: Int
-        val end: Int
-        if (base is StringBuilder && endIndex == base.length) {
-          builder = base
-          start = startIndex
-          end = endIndex + other.length
-        } else {
-          builder = StringBuilder(length + other.length)
-          builder.append(this)
-          start = 0
-          end = length + other.length
-        }
-        other.appendThisTo(builder)
-        Slice(builder, start, end)
-      }
-
-  /** append(this) but taking advantage of fastpath where possible */
-  private fun appendThisTo(builder: StringBuilder) {
-    if (startIndex == 0 && endIndex == base.length) {
-      // there is a fastpath for adding a full string and for adding a full StringBuilder
-      if (base is String) {
-        builder.append(base)
-      } else {
-        builder.append(base as StringBuilder)
-      }
-    } else {
-      builder.append(this)
-    }
-  }
-  fun concat(other: String): Slice {
-    if (base is String && endIndex + other.length <= base.length) {
-      for (i in other.indices) {
-        if (base[i + endIndex] != other[i]) {
-          return concat(of(other))
-        }
-      }
-      return Slice(base, startIndex, endIndex + other.length)
-    }
-    return concat(of(other))
-  }
-  fun concatAnchored(other: Slice): Slice {
-    val result = concat(other)
-    if (result.base !== base) {
-      throw concatRootFailure(other)
-    }
-    return result
-  }
-  fun concatAnchored(other: String): Slice {
-    val result = concat(other)
-    if (result.base !== base) {
-      throw concatRootFailure(other)
-    }
-    return result
-  }
-  private fun concatRootFailure(other: CharSequence): IllegalArgumentException {
-    val maxChange = min(other.length, base.length - endIndex)
-    if (maxChange == 0) {
-      return IllegalArgumentException(
-          "Could not perform anchored concat because we are already at the end of the root ${visualize(base)}")
-    }
-    var firstChange = 0
-    while (firstChange < maxChange) {
-      if (base[endIndex + firstChange] != other[firstChange]) {
-        break
-      }
-      ++firstChange
-    }
-    return IllegalArgumentException(
-        """
-								This ends with '${visualize(base.subSequence(endIndex, endIndex + firstChange + 1))}'
-								cannot concat  '${visualize(other.subSequence(firstChange, firstChange + 1))}
-								"""
-            .trimIndent())
-  }
   fun sameAs(other: CharSequence): Boolean {
     if (length != other.length) {
       return false
@@ -151,151 +52,52 @@ class Slice private constructor(val base: CharSequence, val startIndex: Int, val
     }
     return true
   }
-  fun startsWith(prefix: CharSequence): Boolean {
-    if (length < prefix.length) {
-      return false
-    }
-    for (i in 0 until prefix.length) {
-      if (get(i) != prefix[i]) {
-        return false
-      }
-    }
-    return true
-  }
-  fun endsWith(suffix: CharSequence): Boolean {
-    if (length < suffix.length) {
-      return false
-    }
-    val offset = length - suffix.length
-    for (i in 0 until suffix.length) {
-      if (get(i + offset) != suffix[i]) {
-        return false
-      }
-    }
-    return true
-  }
-  fun indexOf(lookingFor: String): Int {
-    val result =
-        if (base is String) base.indexOf(lookingFor, startIndex)
-        else {
-          (base as StringBuilder).indexOf(lookingFor, startIndex)
-        }
+  fun indexOf(lookingFor: String, startOffset: Int = 0): Int {
+    val result = base.indexOf(lookingFor, startIndex + startOffset)
     return if (result == -1 || result >= endIndex) -1 else result - startIndex
   }
-  fun indexOf(lookingFor: Char): Int {
-    val result =
-        if (base is String) base.indexOf(lookingFor, startIndex)
-        else {
-          (base as StringBuilder).indexOf(lookingFor.toString(), startIndex)
-        }
+  fun indexOf(lookingFor: Char, startOffset: Int = 0): Int {
+    val result = base.indexOf(lookingFor, startIndex + startOffset)
     return if (result == -1 || result >= endIndex) -1 else result - startIndex
   }
-
-  /**
-   * Returns a Slice which represents everything from the start of this string until `lookingFor` is
-   * found. If the string is never found, returns this.
-   */
-  fun until(lookingFor: String): Slice {
-    val idx = indexOf(lookingFor)
-    return if (idx == -1) this else subSequence(0, idx)
-  }
-
-  /**
-   * Asserts that the other string was generated from a call to [.until], and then returns a new
-   * Slice representing everything after that.
-   */
-  fun after(other: Slice): Slice {
-    if (other.isEmpty()) {
-      return this
-    }
-    require(other.base === base && other.startIndex == startIndex && other.endIndex <= endIndex) {
-      "'${visualize(other)}' was not generated by `until` on '${visualize(this)}'"
+  /** Returns a slice at the nth line. Handy for expanding the slice from there. */
+  fun unixLine(count: Int): Slice {
+    check(count > 0)
+    var lineStart = 0
+    for (i in 1 until count) {
+      lineStart = indexOf('\n', lineStart)
+      require(lineStart >= 0) { "This string has only ${i - 1} lines, not $count" }
+      ++lineStart
+    }
+    val lineEnd = indexOf('\n', lineStart)
+    return if (lineEnd == -1) {
+      Slice(base, startIndex + lineStart, endIndex)
+    } else {
+      Slice(base, startIndex + lineStart, startIndex + lineEnd)
     }
-    return Slice(base, other.endIndex, endIndex)
-  }
-
-  /**
-   * Returns the line number of the start of this string. Throws an exception if this isn't based on
-   * a string any longer, because non-contiguous StringPools have been concatenated.
-   */
-  fun baseLineNumberStart(): Int {
-    return baseLineNumberOfOffset(startIndex)
-  }
-
-  /**
-   * Returns the line number of the end of this string. Throws an exception if this isn't based on a
-   * string any longer, because non-contiguous Slices have been concatenated.
-   */
-  fun baseLineNumberEnd(): Int {
-    return baseLineNumberOfOffset(endIndex)
   }
-  private fun baseLineNumberOfOffset(idx: Int): Int {
-    assertStringBased()
-    var lineNumber = 1
-    for (i in 0 until base.length) {
-      if (base[i] == '\n') {
-        ++lineNumber
+  override fun equals(other: Any?) =
+      if (this === other) {
+        true
+      } else if (other is Slice) {
+        sameAs(other)
+      } else {
+        false
       }
-    }
-    return lineNumber
-  }
-  private fun assertStringBased() {
-    check(base is String) {
-      "When you call concat on non-contiguous parts, you lose the connection to the original String."
-    }
-  }
-  override fun equals(anObject: Any?): Boolean {
-    if (this === anObject) {
-      return true
-    } else if (anObject is Slice) {
-      return sameAs(anObject)
-    }
-    return false
-  }
   override fun hashCode(): Int {
     var h = 0
     for (i in indices) {
       h = 31 * h + get(i).code
     }
     return h
   }
-  fun endsAtSamePlace(other: Slice): Boolean {
-    check(base === other.base)
-    return endIndex == other.endIndex
-  }
-
-  companion object {
-    @JvmStatic
-    fun of(base: String, startIndex: Int = 0, endIndex: Int = base.length): Slice {
-      return Slice(base, startIndex, endIndex)
-    }
-    fun concatAll(vararg poolStringsOrStrings: CharSequence): Slice {
-      if (poolStringsOrStrings.isEmpty()) {
-        return empty()
-      }
-      var total = asPool(poolStringsOrStrings[0])
-      for (i in 1 until poolStringsOrStrings.size) {
-        val next = poolStringsOrStrings[i]
-        total = if (next is String) total.concat(next) else total.concat(next as Slice)
-      }
-      return total
-    }
-    private fun visualize(input: CharSequence): String {
-      return input
-          .toString()
-          .replace("\n", "␊")
-          .replace("\r", "␍")
-          .replace(" ", "·")
-          .replace("\t", "»")
-    }
-    private fun asPool(sequence: CharSequence): Slice {
-      return if (sequence is Slice) sequence else of(sequence as String)
-    }
-
-    /** Returns the empty Slice. */
-    @JvmStatic
-    fun empty(): Slice {
-      return Slice("", 0, 0)
-    }
+  /** Returns the underlying string with this slice replaced by the given string. */
+  fun replaceSelfWith(s: String): String {
+    val deltaLength = s.length - length
+    val builder = StringBuilder(base.length + deltaLength)
+    builder.appendRange(base, 0, startIndex)
+    builder.append(s)
+    builder.appendRange(base, endIndex, base.length)
+    return builder.toString()
   }
 }

selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt

@@ -80,7 +80,7 @@ data class Snapshot(
 interface Snapshotter<T> {
   fun snapshot(value: T): Snapshot
 }
-private fun String.efficientReplace(find: String, replaceWith: String): String {
+internal fun String.efficientReplace(find: String, replaceWith: String): String {
   val idx = this.indexOf(find)
   return if (idx == -1) this else this.replace(find, replaceWith)
 }