change_signature.go | Explore in Territory

// RemoveUnusedParameter computes a refactoring to remove the parameter
// indicated by the given range, which must be contained within an unused
// parameter name or field.
//
// This operation is a work in progress. Remaining TODO:
//   - Handle function assignment correctly.
//   - Improve the extra newlines in output.
//   - Stream type checking via ForEachPackage.
//   - Avoid unnecessary additional type checking.
func RemoveUnusedParameter(ctx context.Context, fh file.Handle, rng protocol.Range, snapshot *cache.Snapshot) ([]protocol.DocumentChange, error) { … }

// rewriteSignature rewrites the signature of the declIdx'th declaration in src
// to use the signature of newDecl (described by fset).
//
// TODO(rfindley): I think this operation could be generalized, for example by
// using a concept of a 'nodepath' to correlate nodes between two related
// files.
//
// Note that with its current application, rewriteSignature is expected to
// succeed. Separate bug.Errorf calls are used below (rather than one call at
// the callsite) in order to have greater precision.
func rewriteSignature(fset *token.FileSet, declIdx int, src0 []byte, newDecl *ast.FuncDecl) ([]byte, error) { … }

type paramInfo …

// findParam finds the parameter information spanned by the given range.
func findParam(pgf *parsego.File, rng protocol.Range) (*paramInfo, error) { … }

type signatureRewrite …

// rewriteCalls returns the document changes required to rewrite the
// signature of origDecl to that of newDecl.
//
// This is a rather complicated factoring of the rewrite operation, but is able
// to describe arbitrary rewrites. Specifically, rewriteCalls creates a
// synthetic copy of pkg, where the original function declaration is changed to
// be a trivial wrapper around the new declaration. params and callArgs are
// used to perform this delegation: params must have the same type as origDecl,
// but may have renamed parameters (such as is required for delegating blank
// parameters). callArgs are the arguments of the delegated call (i.e. using
// params).
//
// For example, consider removing the unused 'b' parameter below, rewriting
//
//	func Foo(a, b, c, _ int) int {
//	  return a+c
//	}
//
// To
//
//	func Foo(a, c, _ int) int {
//	  return a+c
//	}
//
// In this case, rewriteCalls is parameterized as follows:
//   - origDecl is the original declaration
//   - newDecl is the new declaration, which is a copy of origDecl less the 'b'
//     parameter.
//   - params is a new parameter list (a, b, c, blank0 int) to be used for the
//     new wrapper.
//   - callArgs is the argument list (a, c, blank0), to be used to call the new
//     delegate.
//
// rewriting is expressed this way so that rewriteCalls can own the details
// of *how* this rewriting is performed. For example, as of writing it names
// the synthetic delegate G_o_p_l_s_foo, but the caller need not know this.
//
// By passing an entirely new declaration, rewriteCalls may be used for
// signature refactorings that may affect the function body, such as removing
// or adding return values.
func rewriteCalls(ctx context.Context, rw signatureRewrite) (map[protocol.DocumentURI][]byte, error) { … }

// reTypeCheck re-type checks orig with new file contents defined by fileMask.
//
// It expects that any newly added imports are already present in the
// transitive imports of orig.
//
// If expectErrors is true, reTypeCheck allows errors in the new package.
// TODO(rfindley): perhaps this should be a filter to specify which errors are
// acceptable.
func reTypeCheck(logf func(string, ...any), orig *cache.Package, fileMask map[protocol.DocumentURI]*ast.File, expectErrors bool) (*types.Package, *types.Info, error) { … }

var goVersionRx …

func remove[T any](s []T, i int) []T { … }

// replaceFileDecl replaces old with new in the file described by pgf.
//
// TODO(rfindley): generalize, and combine with rewriteSignature.
func replaceFileDecl(pgf *parsego.File, old, new ast.Decl) ([]byte, error) { … }

// findDecl finds the index of decl in file.Decls.
//
// TODO: use slices.Index when it is available.
func findDecl(file *ast.File, decl ast.Decl) int { … }
gotools/gopls/internal/golang/change_signature.go
