function() function

resources/META-INF/includes/VimLibraryFunctions.xml

@@ -7,5 +7,6 @@
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.SinFunctionHandler" name="sin"/>
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.ExistsFunctionHandler" name="exists"/>
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.LenFunctionHandler" name="len"/>
+    <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.FunctionFunctionHandler" name="function"/>
   </extensions>
 </idea-plugin>

src/com/maddyhome/idea/vim/vimscript/model/expressions/Scope.kt

@@ -30,8 +30,8 @@ enum class Scope(val c: String) {
   VIM_VARIABLE("v");
 
   companion object {
-    fun getByValue(s: String): Scope {
-      return values().first { it.c == s }
+    fun getByValue(s: String): Scope? {
+      return values().firstOrNull { it.c == s }
     }
   }
 }

src/com/maddyhome/idea/vim/vimscript/model/functions/handlers/FunctionFunctionHandler.kt

@@ -0,0 +1,85 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2021 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.vimscript.model.functions.handlers
+
+import com.intellij.openapi.actionSystem.DataContext
+import com.intellij.openapi.editor.Editor
+import com.maddyhome.idea.vim.ex.ExException
+import com.maddyhome.idea.vim.vimscript.model.Executable
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimDictionary
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimFuncref
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimList
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimString
+import com.maddyhome.idea.vim.vimscript.model.expressions.Expression
+import com.maddyhome.idea.vim.vimscript.model.expressions.Scope
+import com.maddyhome.idea.vim.vimscript.model.functions.FunctionHandler
+import com.maddyhome.idea.vim.vimscript.services.FunctionStorage
+
+object FunctionFunctionHandler : FunctionHandler() {
+  override val name = "function"
+  override val minimumNumberOfArguments: Int = 1
+  override val maximumNumberOfArguments: Int = 3
+
+  override fun doFunction(
+    argumentValues: List<Expression>,
+    editor: Editor,
+    context: DataContext,
+    parent: Executable,
+  ): VimFuncref {
+    val arg1 = argumentValues[0].evaluate(editor, context, parent)
+    if (arg1 !is VimString) {
+      throw ExException("E129: Function name required")
+    }
+    val scopeAndName = arg1.value.extractScopeAndName()
+    val function = FunctionStorage.getFunctionHandlerOrNull(scopeAndName.first, scopeAndName.second, parent)
+      ?: throw ExException("E700: Unknown function: ${if (scopeAndName.first != null) scopeAndName.first!!.c + ":" else ""}${scopeAndName.second}")
+
+    var arglist: VimList? = null
+    var dictionary: VimDictionary? = null
+    val arg2 = argumentValues.getOrNull(1)?.evaluate(editor, context, parent)
+    val arg3 = argumentValues.getOrNull(2)?.evaluate(editor, context, parent)
+
+    if (arg2 is VimDictionary && arg3 is VimDictionary) {
+      throw ExException("E923: Second argument of function() must be a list or a dict")
+    }
+
+    if (arg2 != null) {
+      when (arg2) {
+        is VimList -> arglist = arg2
+        is VimDictionary -> dictionary = arg2
+        else -> throw ExException("E923: Second argument of function() must be a list or a dict")
+      }
+    }
+
+    if (arg3 != null && arg3 !is VimDictionary) {
+      throw ExException("E922: expected a dict")
+    }
+    return VimFuncref(function, arglist ?: VimList(mutableListOf()), dictionary ?: VimDictionary(LinkedHashMap()), VimFuncref.Type.FUNCTION)
+  }
+
+  private fun String.extractScopeAndName(): Pair<Scope?, String> {
+    val colonIndex = this.indexOf(":")
+    if (colonIndex == -1) {
+      return Pair(null, this)
+    }
+    val scopeString = this.substring(0, colonIndex)
+    val nameString = this.substring(colonIndex + 1)
+    return Pair(Scope.getByValue(scopeString), nameString)
+  }
+}

test/org/jetbrains/plugins/ideavim/ex/implementation/functions/FunctionTest.kt

@@ -0,0 +1,128 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2021 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.implementation.functions
+
+import org.jetbrains.plugins.ideavim.SkipNeovimReason
+import org.jetbrains.plugins.ideavim.TestWithoutNeovim
+import org.jetbrains.plugins.ideavim.VimTestCase
+
+class FunctionTest : VimTestCase() {
+
+  fun `test function for built-in function`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function('abs')"))
+    typeText(commandToKeys("echo Ff(-10)"))
+    assertExOutput("10\n")
+
+    typeText(commandToKeys("echo Ff"))
+    assertExOutput("abs\n")
+  }
+
+  fun `test function with arglist`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function('abs', [-10])"))
+    typeText(commandToKeys("echo Ff()"))
+    assertExOutput("10\n")
+
+    typeText(commandToKeys("echo Ff"))
+    assertExOutput("function('abs', [-10])\n")
+  }
+
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN_ERROR)
+  fun `test function for unknown function`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function('unknown')"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E700: Unknown function: unknown")
+  }
+
+  // todo in release 1.9 (good example of multiple exceptions at once)
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN_ERROR)
+  fun `test function with wrong function name`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function(32)"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E129: Function name required")
+  }
+
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN_ERROR)
+  fun `test function with wrong second argument`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function('abs', 10)"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E923: Second argument of function() must be a list or a dict")
+  }
+
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN_ERROR)
+  fun `test function with wrong third argument`() {
+    configureByText("\n")
+    typeText(commandToKeys("let Ff = function('abs', [], 40)"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E922: expected a dict")
+  }
+
+  fun `test redefining a function`() {
+    configureByText("\n")
+    typeText(
+      commandToKeys(
+        """
+      function! SayHi() |
+        echo 'hello' |
+      endfunction
+        """.trimIndent()
+      )
+    )
+    typeText(commandToKeys("let Ff = function('SayHi')"))
+    typeText(commandToKeys("call Ff()"))
+    assertExOutput("hello\n")
+
+    typeText(
+      commandToKeys(
+        """
+      function! SayHi() |
+        echo 'hi' |
+      endfunction
+        """.trimIndent()
+      )
+    )
+    typeText(commandToKeys("call Ff()"))
+    assertExOutput("hi\n")
+
+    typeText(commandToKeys("delfunction! SayHi"))
+  }
+
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN_ERROR)
+  fun `test deleting function`() {
+    configureByText("\n")
+    typeText(
+      commandToKeys(
+        """
+      function! SayHi() |
+        echo 'hello' |
+      endfunction
+        """.trimIndent()
+      )
+    )
+    typeText(commandToKeys("let Ff = function('SayHi')"))
+    typeText(commandToKeys("delfunction! SayHi"))
+    typeText(commandToKeys("call Ff()"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E933: Function was deleted: SayHi")
+  }
+}

vimscript-info/VIMSCRIPT_ROADMAP.md

@@ -25,7 +25,7 @@
 - [x] funcref type
 - [x] lambdas
 - [x] function as method
-- [ ] `function` function
+- [x] `function` function
 - [ ] `funcref` function
 - [ ] dictionary functions  
 - [ ] anonymous functions