Add support for buffer command

resources/META-INF/includes/VimExCommands.xml

@@ -61,5 +61,6 @@
     <vimExCommand implementation="com.maddyhome.idea.vim.ex.handler.PreviousTabHandler" names="tabp[revious],tabN[ext]"/>
     <vimExCommand implementation="com.maddyhome.idea.vim.ex.handler.TabOnlyHandler" names="tabo[nly]"/>
     <vimExCommand implementation="com.maddyhome.idea.vim.ex.handler.BufferListHandler" names="buffers,ls,files"/>
+    <vimExCommand implementation="com.maddyhome.idea.vim.ex.handler.BufferHandler" names="b[uffer],bu[f]"/>
   </extensions>
 </idea-plugin>

src/com/maddyhome/idea/vim/ex/handler/BufferHandler.kt

@@ -0,0 +1,95 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2020 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.maddyhome.idea.vim.ex.handler
+
+import com.intellij.openapi.actionSystem.DataContext
+import com.intellij.openapi.actionSystem.PlatformDataKeys
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.fileEditor.FileEditorManager
+import com.maddyhome.idea.vim.VimPlugin
+import com.maddyhome.idea.vim.ex.CommandHandler
+import com.maddyhome.idea.vim.ex.ExCommand
+import com.maddyhome.idea.vim.ex.flags
+import com.maddyhome.idea.vim.helper.EditorHelper
+
+/**
+ * Handles buffer, buf, bu, b.
+ *
+ * @author John Weigel
+ */
+class BufferHandler : CommandHandler.SingleExecution() {
+  override val argFlags = flags(RangeFlag.RANGE_FORBIDDEN, ArgumentFlag.ARGUMENT_OPTIONAL, Access.READ_ONLY)
+
+  override fun execute(editor: Editor, context: DataContext, cmd: ExCommand): Boolean {
+    val arg = cmd.argument.trim()
+    val overrideModified = arg.startsWith('!')
+    val buffer = if (overrideModified) arg.replace(Regex("^!\\s*"), "") else arg
+    var result = true
+
+    if (buffer.isNotEmpty()) {
+      if (buffer.matches(Regex("^\\d+$"))) {
+        val bufNum = buffer.toInt() - 1
+
+        if (!VimPlugin.getFile().selectFile(bufNum, context)) {
+          VimPlugin.showMessage("Buffer $bufNum does not exist")
+          result = false
+        }
+      } else {
+        val editors = findPartialMatch(context, buffer)
+
+        when(editors.size) {
+          0 -> {
+            VimPlugin.showMessage("No matching buffer for $buffer")
+            result = false
+          }
+          1 -> {
+            if (EditorHelper.hasUnsavedChanges(editor) && !overrideModified) {
+              VimPlugin.showMessage("No write since last change (add ! to override)")
+              result = false
+            }
+            else {
+              VimPlugin.getFile().openFile(EditorHelper.getVirtualFile(editors[0])!!.name, context)
+            }
+          }
+          else -> {
+            VimPlugin.showMessage("More than one match for $buffer")
+            result = false
+          }
+        }
+      }
+    }
+
+    return result
+  }
+
+  private fun findPartialMatch(context: DataContext, fileName: String): List<Editor> {
+    val matchedFiles = mutableListOf<Editor>()
+    val project = PlatformDataKeys.PROJECT.getData(context) ?: return matchedFiles
+
+    for (file in FileEditorManager.getInstance(project).openFiles) {
+      if (file.name.contains(fileName)) {
+        val editor = EditorHelper.getEditor(file) ?: continue
+        matchedFiles.add(editor)
+      }
+    }
+
+    return matchedFiles
+  }
+}
+

src/com/maddyhome/idea/vim/helper/EditorHelper.java

@@ -851,4 +851,21 @@ public static boolean isFileEditor(@NotNull Editor editor) {
   public static boolean isDiffEditor(@NotNull Editor editor) {
     return editor.getEditorKind() == EditorKind.DIFF;
   }
+
+  /**
+   * Checks if the document in the editor is modified.
+   */
+  public static boolean hasUnsavedChanges(@NotNull Editor editor) {
+    int line = 0;
+    Document document = editor.getDocument();
+
+    while (line < document.getLineCount()) {
+      if (document.isLineModified(line)) {
+        return true;
+      }
+      line++;
+    }
+
+    return false;
+  }
 }

test/org/jetbrains/plugins/ideavim/ex/handler/BufferHandlerTest.kt

@@ -0,0 +1,108 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2020 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.jetbrains.plugins.ideavim.ex.handler
+
+import com.maddyhome.idea.vim.helper.StringHelper
+import org.jetbrains.plugins.ideavim.VimTestCase
+
+/**
+ * @author John Weigel
+ */
+class BufferHandlerTest : VimTestCase() {
+  fun testBufferActionByNumber() {
+    configureByFileName("aaa.txt")
+    configureByFileName("bbb.txt")
+    typeText(commandToKeys("buffer 2"))
+
+    assertPluginError(false)
+  }
+
+  fun testBufferActionByName() {
+    configureByFileName("aaa.txt")
+    configureByFileName("bbb.txt")
+    typeText(commandToKeys("buffer aaa"))
+
+    assertPluginError(false)
+  }
+
+  fun testBufferActionWithNoArg() {
+    configureByText("\n")
+    typeText(commandToKeys("buffer"))
+
+    assertPluginError(false)
+  }
+
+  fun testBufferActionWithInvalidBufferNumber() {
+    configureByText("\n")
+    typeText(commandToKeys("buffer 999"))
+
+    assertPluginError(true)
+  }
+
+  fun testBufferActionWithInvalidBufferName() {
+    configureByText("\n")
+    typeText(commandToKeys("buffer invalidbuffer"))
+
+    assertPluginError(true)
+  }
+
+  fun testBufferActionWithModifications() {
+    configureByFileName("aaa.txt")
+    configureByFileName("bbb.txt")
+    typeText(StringHelper.parseKeys("aa<esc>:buffer aaa<enter>"))
+
+    assertPluginError(true)
+  }
+
+  fun testBufferActionWithModificationsOverride() {
+    configureByFileName("aaa.txt")
+    configureByFileName("bbb.txt")
+    typeText(StringHelper.parseKeys("aa<esc>:buffer! aaa<enter>"))
+
+    assertPluginError(false)
+  }
+
+  fun testBufferActionWithMultipleMatches() {
+    configureByFileName("aaa.txt")
+    configureByFileName("aaa2.txt")
+    typeText(commandToKeys("buffer aaa"))
+
+    assertPluginError(true)
+  }
+
+  fun testBufAction() {
+    configureByText("\n")
+    typeText(commandToKeys("buf 1"))
+
+    assertPluginError(false)
+  }
+
+  fun testBuAction() {
+    configureByText("\n")
+    typeText(commandToKeys("bu 1"))
+
+    assertPluginError(false)
+  }
+
+  fun testBAction() {
+    configureByText("\n")
+    typeText(commandToKeys("b 1"))
+
+    assertPluginError(false)
+  }
+}