modfile: Add support for tool lines

Add new tool directive to go.mod parser and functions
to add and drop them.

For golang/go#48429

Change-Id: I37667a69ded9d59ea248ec48ad35c87592103218
Reviewed-on: https://go-review.googlesource.com/c/mod/+/508355
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: ConradIrwin

modfile/rule.go

@@ -43,6 +43,7 @@ type File struct {
 	Exclude   []*Exclude
 	Replace   []*Replace
 	Retract   []*Retract
+	Tool      []*Tool
 
 	Syntax *FileSyntax
 }
@@ -93,6 +94,12 @@ type Retract struct {
 	Syntax    *Line
 }
 
+// A Tool is a single tool statement.
+type Tool struct {
+	Path   string
+	Syntax *Line
+}
+
 // A VersionInterval represents a range of versions with upper and lower bounds.
 // Intervals are closed: both bounds are included. When Low is equal to High,
 // the interval may refer to a single version ('v1.2.3') or an interval
@@ -297,7 +304,7 @@ func parseToFile(file string, data []byte, fix VersionFixer, strict bool) (parse
 					})
 				}
 				continue
-			case "module", "godebug", "require", "exclude", "replace", "retract":
+			case "module", "godebug", "require", "exclude", "replace", "retract", "tool":
 				for _, l := range x.Line {
 					f.add(&errs, x, l, x.Token[0], l.Token, fix, strict)
 				}
@@ -509,6 +516,21 @@ func (f *File) add(errs *ErrorList, block *LineBlock, line *Line, verb string, a
 			Syntax:          line,
 		}
 		f.Retract = append(f.Retract, retract)
+
+	case "tool":
+		if len(args) != 1 {
+			errorf("tool directive expects exactly one argument")
+			return
+		}
+		s, err := parseString(&args[0])
+		if err != nil {
+			errorf("invalid quoted string: %v", err)
+			return
+		}
+		f.Tool = append(f.Tool, &Tool{
+			Path:   s,
+			Syntax: line,
+		})
 	}
 }
 
@@ -1567,6 +1589,36 @@ func (f *File) DropRetract(vi VersionInterval) error {
 	return nil
 }
 
+// AddTool adds a new tool directive with the given path.
+// It does nothing if the tool line already exists.
+func (f *File) AddTool(path string) error {
+	for _, t := range f.Tool {
+		if t.Path == path {
+			return nil
+		}
+	}
+
+	f.Tool = append(f.Tool, &Tool{
+		Path:   path,
+		Syntax: f.Syntax.addLine(nil, "tool", path),
+	})
+
+	f.SortBlocks()
+	return nil
+}
+
+// RemoveTool removes a tool directive with the given path.
+// It does nothing if no such tool directive exists.
+func (f *File) DropTool(path string) error {
+	for _, t := range f.Tool {
+		if t.Path == path {
+			t.Syntax.markRemoved()
+			*t = Tool{}
+		}
+	}
+	return nil
+}
+
 func (f *File) SortBlocks() {
 	f.removeDups() // otherwise sorting is unsafe
 
@@ -1593,9 +1645,9 @@ func (f *File) SortBlocks() {
 	}
 }
 
-// removeDups removes duplicate exclude and replace directives.
+// removeDups removes duplicate exclude, replace and tool directives.
 //
-// Earlier exclude directives take priority.
+// Earlier exclude and tool directives take priority.
 //
 // Later replace directives take priority.
 //
@@ -1605,10 +1657,10 @@ func (f *File) SortBlocks() {
 // retract directives are not de-duplicated since comments are
 // meaningful, and versions may be retracted multiple times.
 func (f *File) removeDups() {
-	removeDups(f.Syntax, &f.Exclude, &f.Replace)
+	removeDups(f.Syntax, &f.Exclude, &f.Replace, &f.Tool)
 }
 
-func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace) {
+func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace, tool *[]*Tool) {
 	kill := make(map[*Line]bool)
 
 	// Remove duplicate excludes.
@@ -1649,6 +1701,24 @@ func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace) {
 	}
 	*replace = repl
 
+	if tool != nil {
+		haveTool := make(map[string]bool)
+		for _, t := range *tool {
+			if haveTool[t.Path] {
+				kill[t.Syntax] = true
+				continue
+			}
+			haveTool[t.Path] = true
+		}
+		var newTool []*Tool
+		for _, t := range *tool {
+			if !kill[t.Syntax] {
+				newTool = append(newTool, t)
+			}
+		}
+		*tool = newTool
+	}
+
 	// Duplicate require and retract directives are not removed.
 
 	// Drop killed statements from the syntax tree.

modfile/rule_test.go

@@ -1714,6 +1714,72 @@ var dropGodebugTests = []struct {
 	},
 }
 
+var addToolTests = []struct {
+	desc, in, path, want string
+}{
+	{
+		`add_first`,
+		`module example.com/m`,
+		`example.com/tool/v1`,
+		`module example.com/m
+		tool example.com/tool/v1`,
+	},
+	{
+		`sorted_correctly`,
+		`module example.com/m
+		tool example.com/tool2
+		`,
+		`example.com/tool1`,
+		`module example.com/m
+		tool (
+			example.com/tool1
+			example.com/tool2
+		)`,
+	},
+	{
+		`duplicates_ignored`,
+		`module example.com/m
+		tool example.com/tool1
+		`,
+		`example.com/tool1`,
+		`module example.com/m
+		tool example.com/tool1`,
+	},
+}
+
+var dropToolTests = []struct {
+	desc, in, path, want string
+}{
+	{
+		`only`,
+		`module example.com/m
+		tool example.com/tool1`,
+		`example.com/tool1`,
+		`module example.com/m`,
+	},
+	{
+		`parenthesized`,
+		`module example.com/m
+		tool (
+			example.com/tool1
+			example.com/tool2
+		)`,
+		`example.com/tool1`,
+		`module example.com/m
+		tool example.com/tool2`,
+	},
+	{
+		`missing`,
+		`module example.com/m
+		tool (
+		example.com/tool2
+		)`,
+		`example.com/tool1`,
+		`module example.com/m
+		tool example.com/tool2`,
+	},
+}
+
 func fixV(path, version string) (string, error) {
 	if path != "example.com/m" {
 		return "", fmt.Errorf("module path must be example.com/m")
@@ -2051,6 +2117,7 @@ func TestAddOnEmptyFile(t *testing.T) {
 				t.Fatal(err)
 			}
 			got, err := f.Format()
+
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -2061,3 +2128,65 @@ func TestAddOnEmptyFile(t *testing.T) {
 		})
 	}
 }
+
+func TestAddTool(t *testing.T) {
+	for _, tt := range addToolTests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inFile, err := Parse("in", []byte(tt.in), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if err := inFile.AddTool(tt.path); err != nil {
+				t.Fatal(err)
+			}
+			inFile.Cleanup()
+			got, err := inFile.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			outFile, err := Parse("out", []byte(tt.want), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			want, err := outFile.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !bytes.Equal(got, want) {
+				t.Fatalf("got:\n%s\nwant:\n%s", got, want)
+			}
+		})
+	}
+}
+
+func TestDropTool(t *testing.T) {
+	for _, tt := range dropToolTests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inFile, err := Parse("in", []byte(tt.in), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if err := inFile.DropTool(tt.path); err != nil {
+				t.Fatal(err)
+			}
+			inFile.Cleanup()
+			got, err := inFile.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			outFile, err := Parse("out", []byte(tt.want), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			want, err := outFile.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !bytes.Equal(got, want) {
+				t.Fatalf("got:\n%s\nwant:\n%s", got, want)
+			}
+		})
+	}
+}

modfile/work.go

@@ -331,5 +331,5 @@ func (f *WorkFile) SortBlocks() {
 // retract directives are not de-duplicated since comments are
 // meaningful, and versions may be retracted multiple times.
 func (f *WorkFile) removeDups() {
-	removeDups(f.Syntax, nil, &f.Replace)
+	removeDups(f.Syntax, nil, &f.Replace, nil)
 }