feat: Signature help (#547)

closes #18

fixtures/signature_help/calls.php

@@ -0,0 +1,66 @@
+<?php
+
+namespace Foo;
+
+class Test
+{
+    /**
+     * Constructor comment goes here
+     *
+     * @param string $first  First param
+     * @param int    $second Second param
+     * @param Test   $third  Third param with a longer description
+     */
+    public function __construct(string $first, int $second, Test $third)
+    {
+    }
+
+    /**
+     * Function doc
+     *
+     * @param SomethingElse $a A param with a different doc type
+     * @param int|null      $b Param with default value
+     */
+    public function foo(\DateTime $a, int $b = null)
+    {
+    }
+
+    public static function bar($a)
+    {
+    }
+
+    /**
+     * Method with no params
+     */
+    public function baz()
+    {
+    }
+}
+
+/**
+ * @param int  $i Global function param one
+ * @param bool $b Default false param
+ * @param Test|null ...$things Test things
+ */
+function foo(int $i, bool $b = false, Test ...$things = null)
+{
+}
+
+$t = new Test();
+$t = new Test(1, );
+$t->foo();
+$t->foo(1,  
+$t->foo(1,);
+$t->baz();
+
+foo(
+    1,
+    foo(1, 2,  
+);
+
+Test::bar();
+
+new $foo();
+new $foo(1, );
+
+new NotExist();

src/Definition.php

@@ -99,6 +99,13 @@ class Definition
      */
     public $documentation;
 
+    /**
+     * Signature information if this definition is for a FunctionLike, for use in textDocument/signatureHelp
+     *
+     * @var SignatureInformation
+     */
+    public $signatureInformation;
+
     /**
      * Yields the definitons of all ancestor classes (the Definition fqn is yielded as key)
      *

src/DefinitionResolver.php

@@ -7,6 +7,7 @@
 use LanguageServer\Protocol\SymbolInformation;
 use Microsoft\PhpParser;
 use Microsoft\PhpParser\Node;
+use Microsoft\PhpParser\FunctionLike;
 use phpDocumentor\Reflection\{
     DocBlock, DocBlockFactory, Fqsen, Type, TypeResolver, Types
 };
@@ -34,6 +35,13 @@ class DefinitionResolver
      */
     private $docBlockFactory;
 
+    /**
+     * Creates SignatureInformation
+     *
+     * @var SignatureInformationFactory
+     */
+    private $signatureInformationFactory;
+
     /**
      * @param ReadableIndex $index
      */
@@ -42,6 +50,7 @@ public function __construct(ReadableIndex $index)
         $this->index = $index;
         $this->typeResolver = new TypeResolver;
         $this->docBlockFactory = DocBlockFactory::createInstance();
+        $this->signatureInformationFactory = new SignatureInformationFactory($this);
     }
 
     /**
@@ -232,6 +241,10 @@ public function createDefinitionFromNode(Node $node, string $fqn = null): Defini
             $def->documentation = $this->getDocumentationFromNode($node);
         }
 
+        if ($node instanceof FunctionLike) {
+            $def->signatureInformation = $this->signatureInformationFactory->create($node);
+        }
+
         return $def;
     }
 

src/LanguageServer.php

@@ -9,7 +9,8 @@
     TextDocumentSyncKind,
     Message,
     InitializeResult,
-    CompletionOptions
+    CompletionOptions,
+    SignatureHelpOptions
 };
 use LanguageServer\FilesFinder\{FilesFinder, ClientFilesFinder, FileSystemFilesFinder};
 use LanguageServer\ContentRetriever\{ContentRetriever, ClientContentRetriever, FileSystemContentRetriever};
@@ -275,6 +276,10 @@ public function initialize(ClientCapabilities $capabilities, string $rootPath =
             $serverCapabilities->completionProvider = new CompletionOptions;
             $serverCapabilities->completionProvider->resolveProvider = false;
             $serverCapabilities->completionProvider->triggerCharacters = ['$', '>'];
+
+            $serverCapabilities->signatureHelpProvider = new SignatureHelpOptions();
+            $serverCapabilities->signatureHelpProvider->triggerCharacters = ['(', ','];
+
             // Support global references
             $serverCapabilities->xworkspaceReferencesProvider = true;
             $serverCapabilities->xdefinitionProvider = true;

src/Protocol/ParameterInformation.php

@@ -23,4 +23,17 @@ class ParameterInformation
      * @var string|null
      */
     public $documentation;
+
+    /**
+     * Create ParameterInformation
+     *
+     * @param string $label         The label of this signature. Will be shown in the UI.
+     * @param string $documentation The human-readable doc-comment of this signature. Will be shown in the UI but can
+     *                              be omitted.
+     */
+    public function __construct(string $label, string $documentation = null)
+    {
+        $this->label = $label;
+        $this->documentation = $documentation;
+    }
 }

src/Protocol/SignatureHelp.php

@@ -29,4 +29,18 @@ class SignatureHelp
      * @var int|null
      */
     public $activeParameter;
+
+    /**
+     * Create a SignatureHelp
+     *
+     * @param SignatureInformation[] $signatures      List of signature information
+     * @param int|null               $activeSignature The active signature, zero based
+     * @param int|null               $activeParameter The active parameter, zero based
+     */
+    public function __construct(array $signatures = [], $activeSignature = null, int $activeParameter = null)
+    {
+        $this->signatures = $signatures;
+        $this->activeSignature = $activeSignature;
+        $this->activeParameter = $activeParameter;
+    }
 }

src/Protocol/SignatureInformation.php

@@ -31,4 +31,19 @@ class SignatureInformation
      * @var ParameterInformation[]|null
      */
     public $parameters;
+
+    /**
+     * Create a SignatureInformation
+     *
+     * @param string $label               The label of this signature. Will be shown in the UI.
+     * @param ParameterInformation[]|null The parameters of this signature
+     * @param string|null                 The human-readable doc-comment of this signature. Will be shown in the UI
+     *                                    but can be omitted.
+     */
+    public function __construct(string $label, array $parameters = null, string $documentation = null)
+    {
+        $this->label = $label;
+        $this->parameters = $parameters;
+        $this->documentation = $documentation;
+    }
 }

src/Server/TextDocument.php

@@ -4,7 +4,7 @@
 namespace LanguageServer\Server;
 
 use LanguageServer\{
-    CompletionProvider, LanguageClient, PhpDocument, PhpDocumentLoader, DefinitionResolver
+    CompletionProvider, SignatureHelpProvider, LanguageClient, PhpDocument, PhpDocumentLoader, DefinitionResolver
 };
 use LanguageServer\Index\ReadableIndex;
 use LanguageServer\Protocol\{
@@ -59,6 +59,11 @@ class TextDocument
      */
     protected $completionProvider;
 
+    /**
+     * @var SignatureHelpProvider
+     */
+    protected $signatureHelpProvider;
+
     /**
      * @var ReadableIndex
      */
@@ -94,6 +99,7 @@ public function __construct(
         $this->client = $client;
         $this->definitionResolver = $definitionResolver;
         $this->completionProvider = new CompletionProvider($this->definitionResolver, $index);
+        $this->signatureHelpProvider = new SignatureHelpProvider($this->definitionResolver, $index, $documentLoader);
         $this->index = $index;
         $this->composerJson = $composerJson;
         $this->composerLock = $composerLock;
@@ -237,6 +243,23 @@ public function references(
         });
     }
 
+    /**
+     * The signature help request is sent from the client to the server to request signature information at a given
+     * cursor position.
+     *
+     * @param TextDocumentIdentifier $textDocument The text document
+     * @param Position               $position     The position inside the text document
+     *
+     * @return Promise <SignatureHelp>
+     */
+    public function signatureHelp(TextDocumentIdentifier $textDocument, Position $position): Promise
+    {
+        return coroutine(function () use ($textDocument, $position) {
+            $document = yield $this->documentLoader->getOrLoad($textDocument->uri);
+            return $this->signatureHelpProvider->getSignatureHelp($document, $position);
+        });
+    }
+
     /**
      * The goto definition request is sent from the client to the server to resolve the definition location of a symbol
      * at a given text document position.