LanguageClient: use internal filtering if we got all completions

... at the current position. This reduces the amount of requested
completions.

Change-Id: I0fa35269bc123513217e3b3abd2c921bd92d8d10
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/texteditor/codeassist/codeassistant.cpp

@@ -51,6 +51,7 @@ public:
     void displayProposal(IAssistProposal *newProposal, AssistReason reason);
     bool isDisplayingProposal() const;
     bool isWaitingForProposal() const;
+    QString proposalPrefix() const;
 
     void notifyChange();
     bool hasContext() const;
@@ -134,7 +135,7 @@ void CodeAssistantPrivate::invoke(AssistKind kind, IAssistProvider *provider)
     stopAutomaticProposalTimer();
 
     if (isDisplayingProposal() && m_assistKind == kind && !m_proposal->isFragile()
-        && m_proposal->supportsPrefix()) {
+        && m_proposal->supportsPrefixFiltering(proposalPrefix())) {
         m_proposalWidget->setReason(ExplicitlyInvoked);
         m_proposalWidget->updateProposal(m_editorWidget->textAt(
                         m_proposal->basePosition(),
@@ -426,6 +427,14 @@ bool CodeAssistantPrivate::isWaitingForProposal() const
     return m_requestRunner != nullptr || m_asyncProcessor != nullptr;
 }
 
+QString CodeAssistantPrivate::proposalPrefix() const
+{
+    if (!isDisplayingProposal())
+        return {};
+    return m_editorWidget->textAt(m_proposal->basePosition(),
+                                  m_editorWidget->position() - m_proposal->basePosition());
+}
+
 void CodeAssistantPrivate::invalidateCurrentRequestData()
 {
     m_asyncProcessor = nullptr;
@@ -468,14 +477,15 @@ void CodeAssistantPrivate::notifyChange()
         QTC_ASSERT(m_proposal, return);
         if (m_editorWidget->position() < m_proposal->basePosition()) {
             destroyContext();
-        } else if (m_proposal->supportsPrefix()) {
-            m_proposalWidget->updateProposal(
-                m_editorWidget->textAt(m_proposal->basePosition(),
-                                     m_editorWidget->position() - m_proposal->basePosition()));
-            if (!isDisplayingProposal())
-                requestActivationCharProposal();
         } else {
-            requestProposal(m_proposal->reason(), m_assistKind, m_requestProvider, true);
+            const QString prefix = proposalPrefix();
+            if (m_proposal->supportsPrefixFiltering(prefix)) {
+                m_proposalWidget->updateProposal(prefix);
+                if (!isDisplayingProposal())
+                    requestActivationCharProposal();
+            } else {
+                requestProposal(m_proposal->reason(), m_assistKind, m_requestProvider, true);
+            }
         }
     }
 }

src/plugins/texteditor/codeassist/iassistproposal.cpp

@@ -68,9 +68,9 @@ bool IAssistProposal::isFragile() const
     return m_isFragile;
 }
 
-bool IAssistProposal::supportsPrefix() const
+bool IAssistProposal::supportsPrefixFiltering(const QString &prefix) const
 {
-    return m_supportsPrefix;
+    return !m_prefixChecker || m_prefixChecker(prefix);
 }
 
 /*!
@@ -103,9 +103,9 @@ void IAssistProposal::setFragile(bool fragile)
     m_isFragile = fragile;
 }
 
-void IAssistProposal::setSupportsPrefix(bool supportsPrefix)
+void IAssistProposal::setPrefixChecker(const PrefixChecker checker)
 {
-    m_supportsPrefix = supportsPrefix;
+    m_prefixChecker = checker;
 }
 
 /*!

src/plugins/texteditor/codeassist/iassistproposal.h

@@ -23,7 +23,7 @@ public:
 
     int basePosition() const;
     bool isFragile() const;
-    bool supportsPrefix() const;
+    bool supportsPrefixFiltering(const QString &prefix) const;
     virtual bool hasItemsToPropose(const QString &, AssistReason) const { return true; }
     virtual bool isCorrective(TextEditorWidget *editorWidget) const;
     virtual void makeCorrection(TextEditorWidget *editorWidget);
@@ -31,18 +31,20 @@ public:
     virtual IAssistProposalWidget *createWidget() const = 0;
 
     void setFragile(bool fragile);
-    void setSupportsPrefix(bool supportsPrefix);
 
     Utils::Id id() const { return m_id; }
 
     AssistReason reason() const { return m_reason; }
     void setReason(const AssistReason &reason) { m_reason = reason; }
 
+    using PrefixChecker = std::function<bool(const QString &)>;
+    void setPrefixChecker(const PrefixChecker checker);
+
 protected:
     Utils::Id m_id;
     int m_basePosition;
     bool m_isFragile = false;
-    bool m_supportsPrefix = true;
+    PrefixChecker m_prefixChecker;
     AssistReason m_reason = IdleEditor;
 };