gopls/internal/codeaction: replace all occurrences of expression (refactor.extract.variable.all)

gopls/doc/features/transformation.md

@@ -72,6 +72,7 @@ Gopls supports the following code actions:
 - [`refactor.extract.method`](#extract)
 - [`refactor.extract.toNewFile`](#extract.toNewFile)
 - [`refactor.extract.variable`](#extract)
+- [`refactor.extract.variable.all`](#extract)
 - [`refactor.inline.call`](#refactor.inline.call)
 - [`refactor.rewrite.changeQuote`](#refactor.rewrite.changeQuote)
 - [`refactor.rewrite.fillStruct`](#refactor.rewrite.fillStruct)
@@ -313,11 +314,18 @@ newly created declaration that contains the selected code:
   will be a method of the same receiver type.
 
 - **`refactor.extract.variable`** replaces an expression by a reference to a new
-  local variable named `x` initialized by the expression:
+  local variable named `newVar` initialized by the expression:
 
-  ![Before extracting a var](../assets/extract-var-before.png)
+  ![Before extracting a var](../assets/extract-expressions-before.png)
   ![After extracting a var](../assets/extract-var-after.png)
 
+- **`refactor.extract.variable.all`** replaces all occurrences of the selected expression
+within the function with a reference to a new local variable named `newVar`.
+This extracts the expression once and reuses it wherever it appears in the function.
+
+  ![Before extracting all expressions](../assets/extract-expressions-before.png)
+  ![After extracting all expressions](../assets/extract-expressions-after.png)
+
 If the default name for the new declaration is already in use, gopls
 generates a fresh name.
 

gopls/doc/release/v0.17.0.md

@@ -84,3 +84,8 @@ from the context of the call.
 The new `yield` analyzer detects mistakes using the `yield` function
 in a Go 1.23 iterator, such as failure to check its boolean result and
 break out of a loop.
+
+## Extract all occurrences of the same expression under selection
+When you have multiple instances of the same expression in a function,
+you can use this code action to extract it into a variable.
+All occurrences of the expression will be replaced with a reference to the new variable.

gopls/internal/golang/codeaction.go

@@ -27,6 +27,7 @@ import (
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/gopls/internal/protocol/command"
 	"golang.org/x/tools/gopls/internal/settings"
+	"golang.org/x/tools/gopls/internal/util/safetoken"
 	"golang.org/x/tools/gopls/internal/util/typesutil"
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/imports"
@@ -236,6 +237,7 @@ var codeActionProducers = [...]codeActionProducer{
 	{kind: settings.RefactorExtractFunction, fn: refactorExtractFunction},
 	{kind: settings.RefactorExtractMethod, fn: refactorExtractMethod},
 	{kind: settings.RefactorExtractToNewFile, fn: refactorExtractToNewFile},
+	{kind: settings.RefactorExtractAllOccursOfExpr, fn: refactorExtractAllOccursOfExpr},
 	{kind: settings.RefactorExtractVariable, fn: refactorExtractVariable},
 	{kind: settings.RefactorInlineCall, fn: refactorInlineCall, needPkg: true},
 	{kind: settings.RefactorRewriteChangeQuote, fn: refactorRewriteChangeQuote},
@@ -452,12 +454,32 @@ func refactorExtractMethod(ctx context.Context, req *codeActionsRequest) error {
 // refactorExtractVariable produces "Extract variable" code actions.
 // See [extractVariable] for command implementation.
 func refactorExtractVariable(ctx context.Context, req *codeActionsRequest) error {
-	if _, _, ok, _ := canExtractVariable(req.start, req.end, req.pgf.File); ok {
+	if _, ok, _ := canExtractVariable(req.start, req.end, req.pgf.File, false); ok {
 		req.addApplyFixAction("Extract variable", fixExtractVariable, req.loc)
 	}
 	return nil
 }
 
+// refactorExtractAllOccursOfExpr produces "Extract n occurrences of expression" code action.
+// See [extractAllOccursOfExpr] for command implementation.
+func refactorExtractAllOccursOfExpr(ctx context.Context, req *codeActionsRequest) error {
+	// Don't suggest if only one expr is found,
+	// otherwise it will duplicate with [refactorExtractVariable]
+	if exprs, ok, _ := canExtractVariable(req.start, req.end, req.pgf.File, true); ok && len(exprs) > 1 {
+		startOffset, err := safetoken.Offset(req.pgf.Tok, exprs[0].Pos())
+		if err != nil {
+			return nil
+		}
+		endOffset, err := safetoken.Offset(req.pgf.Tok, exprs[0].End())
+		if err != nil {
+			return nil
+		}
+		expr := req.pgf.Src[startOffset:endOffset]
+		req.addApplyFixAction(fmt.Sprintf("Extract %d occurrences of %s", len(exprs), expr), fixExtractAllOccursOfExpr, req.loc)
+	}
+	return nil
+}
+
 // refactorExtractToNewFile produces "Extract declarations to new file" code actions.
 // See [server.commandHandler.ExtractToNewFile] for command implementation.
 func refactorExtractToNewFile(ctx context.Context, req *codeActionsRequest) error {