rule.go

Documentation: cmd/vendor/golang.org/x/mod/modfile

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package modfile implements a parser and formatter for go.mod files.
     6  //
     7  // The go.mod syntax is described in
     8  // https://pkg.go.dev/cmd/go/#hdr-The_go_mod_file.
     9  //
    10  // The [Parse] and [ParseLax] functions both parse a go.mod file and return an
    11  // abstract syntax tree. ParseLax ignores unknown statements and may be used to
    12  // parse go.mod files that may have been developed with newer versions of Go.
    13  //
    14  // The [File] struct returned by Parse and ParseLax represent an abstract
    15  // go.mod file. File has several methods like [File.AddNewRequire] and
    16  // [File.DropReplace] that can be used to programmatically edit a file.
    17  //
    18  // The [Format] function formats a File back to a byte slice which can be
    19  // written to a file.
    20  package modfile
    21  
    22  import (
    23  	"errors"
    24  	"fmt"
    25  	"path/filepath"
    26  	"sort"
    27  	"strconv"
    28  	"strings"
    29  	"unicode"
    30  
    31  	"golang.org/x/mod/internal/lazyregexp"
    32  	"golang.org/x/mod/module"
    33  	"golang.org/x/mod/semver"
    34  )
    35  
    36  // A File is the parsed, interpreted form of a go.mod file.
    37  type File struct {
    38  	Module    *Module
    39  	Go        *Go
    40  	Toolchain *Toolchain
    41  	Require   []*Require
    42  	Exclude   []*Exclude
    43  	Replace   []*Replace
    44  	Retract   []*Retract
    45  
    46  	Syntax *FileSyntax
    47  }
    48  
    49  // A Module is the module statement.
    50  type Module struct {
    51  	Mod        module.Version
    52  	Deprecated string
    53  	Syntax     *Line
    54  }
    55  
    56  // A Go is the go statement.
    57  type Go struct {
    58  	Version string // "1.23"
    59  	Syntax  *Line
    60  }
    61  
    62  // A Toolchain is the toolchain statement.
    63  type Toolchain struct {
    64  	Name   string // "go1.21rc1"
    65  	Syntax *Line
    66  }
    67  
    68  // An Exclude is a single exclude statement.
    69  type Exclude struct {
    70  	Mod    module.Version
    71  	Syntax *Line
    72  }
    73  
    74  // A Replace is a single replace statement.
    75  type Replace struct {
    76  	Old    module.Version
    77  	New    module.Version
    78  	Syntax *Line
    79  }
    80  
    81  // A Retract is a single retract statement.
    82  type Retract struct {
    83  	VersionInterval
    84  	Rationale string
    85  	Syntax    *Line
    86  }
    87  
    88  // A VersionInterval represents a range of versions with upper and lower bounds.
    89  // Intervals are closed: both bounds are included. When Low is equal to High,
    90  // the interval may refer to a single version ('v1.2.3') or an interval
    91  // ('[v1.2.3, v1.2.3]'); both have the same representation.
    92  type VersionInterval struct {
    93  	Low, High string
    94  }
    95  
    96  // A Require is a single require statement.
    97  type Require struct {
    98  	Mod      module.Version
    99  	Indirect bool // has "// indirect" comment
   100  	Syntax   *Line
   101  }
   102  
   103  func (r *Require) markRemoved() {
   104  	r.Syntax.markRemoved()
   105  	*r = Require{}
   106  }
   107  
   108  func (r *Require) setVersion(v string) {
   109  	r.Mod.Version = v
   110  
   111  	if line := r.Syntax; len(line.Token) > 0 {
   112  		if line.InBlock {
   113  			// If the line is preceded by an empty line, remove it; see
   114  			// https://golang.org/issue/33779.
   115  			if len(line.Comments.Before) == 1 && len(line.Comments.Before[0].Token) == 0 {
   116  				line.Comments.Before = line.Comments.Before[:0]
   117  			}
   118  			if len(line.Token) >= 2 { // example.com v1.2.3
   119  				line.Token[1] = v
   120  			}
   121  		} else {
   122  			if len(line.Token) >= 3 { // require example.com v1.2.3
   123  				line.Token[2] = v
   124  			}
   125  		}
   126  	}
   127  }
   128  
   129  // setIndirect sets line to have (or not have) a "// indirect" comment.
   130  func (r *Require) setIndirect(indirect bool) {
   131  	r.Indirect = indirect
   132  	line := r.Syntax
   133  	if isIndirect(line) == indirect {
   134  		return
   135  	}
   136  	if indirect {
   137  		// Adding comment.
   138  		if len(line.Suffix) == 0 {
   139  			// New comment.
   140  			line.Suffix = []Comment{{Token: "// indirect", Suffix: true}}
   141  			return
   142  		}
   143  
   144  		com := &line.Suffix[0]
   145  		text := strings.TrimSpace(strings.TrimPrefix(com.Token, string(slashSlash)))
   146  		if text == "" {
   147  			// Empty comment.
   148  			com.Token = "// indirect"
   149  			return
   150  		}
   151  
   152  		// Insert at beginning of existing comment.
   153  		com.Token = "// indirect; " + text
   154  		return
   155  	}
   156  
   157  	// Removing comment.
   158  	f := strings.TrimSpace(strings.TrimPrefix(line.Suffix[0].Token, string(slashSlash)))
   159  	if f == "indirect" {
   160  		// Remove whole comment.
   161  		line.Suffix = nil
   162  		return
   163  	}
   164  
   165  	// Remove comment prefix.
   166  	com := &line.Suffix[0]
   167  	i := strings.Index(com.Token, "indirect;")
   168  	com.Token = "//" + com.Token[i+len("indirect;"):]
   169  }
   170  
   171  // isIndirect reports whether line has a "// indirect" comment,
   172  // meaning it is in go.mod only for its effect on indirect dependencies,
   173  // so that it can be dropped entirely once the effective version of the
   174  // indirect dependency reaches the given minimum version.
   175  func isIndirect(line *Line) bool {
   176  	if len(line.Suffix) == 0 {
   177  		return false
   178  	}
   179  	f := strings.Fields(strings.TrimPrefix(line.Suffix[0].Token, string(slashSlash)))
   180  	return (len(f) == 1 && f[0] == "indirect" || len(f) > 1 && f[0] == "indirect;")
   181  }
   182  
   183  func (f *File) AddModuleStmt(path string) error {
   184  	if f.Syntax == nil {
   185  		f.Syntax = new(FileSyntax)
   186  	}
   187  	if f.Module == nil {
   188  		f.Module = &Module{
   189  			Mod:    module.Version{Path: path},
   190  			Syntax: f.Syntax.addLine(nil, "module", AutoQuote(path)),
   191  		}
   192  	} else {
   193  		f.Module.Mod.Path = path
   194  		f.Syntax.updateLine(f.Module.Syntax, "module", AutoQuote(path))
   195  	}
   196  	return nil
   197  }
   198  
   199  func (f *File) AddComment(text string) {
   200  	if f.Syntax == nil {
   201  		f.Syntax = new(FileSyntax)
   202  	}
   203  	f.Syntax.Stmt = append(f.Syntax.Stmt, &CommentBlock{
   204  		Comments: Comments{
   205  			Before: []Comment{
   206  				{
   207  					Token: text,
   208  				},
   209  			},
   210  		},
   211  	})
   212  }
   213  
   214  type VersionFixer func(path, version string) (string, error)
   215  
   216  // errDontFix is returned by a VersionFixer to indicate the version should be
   217  // left alone, even if it's not canonical.
   218  var dontFixRetract VersionFixer = func(_, vers string) (string, error) {
   219  	return vers, nil
   220  }
   221  
   222  // Parse parses and returns a go.mod file.
   223  //
   224  // file is the name of the file, used in positions and errors.
   225  //
   226  // data is the content of the file.
   227  //
   228  // fix is an optional function that canonicalizes module versions.
   229  // If fix is nil, all module versions must be canonical ([module.CanonicalVersion]
   230  // must return the same string).
   231  func Parse(file string, data []byte, fix VersionFixer) (*File, error) {
   232  	return parseToFile(file, data, fix, true)
   233  }
   234  
   235  // ParseLax is like Parse but ignores unknown statements.
   236  // It is used when parsing go.mod files other than the main module,
   237  // under the theory that most statement types we add in the future will
   238  // only apply in the main module, like exclude and replace,
   239  // and so we get better gradual deployments if old go commands
   240  // simply ignore those statements when found in go.mod files
   241  // in dependencies.
   242  func ParseLax(file string, data []byte, fix VersionFixer) (*File, error) {
   243  	return parseToFile(file, data, fix, false)
   244  }
   245  
   246  func parseToFile(file string, data []byte, fix VersionFixer, strict bool) (parsed *File, err error) {
   247  	fs, err := parse(file, data)
   248  	if err != nil {
   249  		return nil, err
   250  	}
   251  	f := &File{
   252  		Syntax: fs,
   253  	}
   254  	var errs ErrorList
   255  
   256  	// fix versions in retract directives after the file is parsed.
   257  	// We need the module path to fix versions, and it might be at the end.
   258  	defer func() {
   259  		oldLen := len(errs)
   260  		f.fixRetract(fix, &errs)
   261  		if len(errs) > oldLen {
   262  			parsed, err = nil, errs
   263  		}
   264  	}()
   265  
   266  	for _, x := range fs.Stmt {
   267  		switch x := x.(type) {
   268  		case *Line:
   269  			f.add(&errs, nil, x, x.Token[0], x.Token[1:], fix, strict)
   270  
   271  		case *LineBlock:
   272  			if len(x.Token) > 1 {
   273  				if strict {
   274  					errs = append(errs, Error{
   275  						Filename: file,
   276  						Pos:      x.Start,
   277  						Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
   278  					})
   279  				}
   280  				continue
   281  			}
   282  			switch x.Token[0] {
   283  			default:
   284  				if strict {
   285  					errs = append(errs, Error{
   286  						Filename: file,
   287  						Pos:      x.Start,
   288  						Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
   289  					})
   290  				}
   291  				continue
   292  			case "module", "require", "exclude", "replace", "retract":
   293  				for _, l := range x.Line {
   294  					f.add(&errs, x, l, x.Token[0], l.Token, fix, strict)
   295  				}
   296  			}
   297  		}
   298  	}
   299  
   300  	if len(errs) > 0 {
   301  		return nil, errs
   302  	}
   303  	return f, nil
   304  }
   305  
   306  var GoVersionRE = lazyregexp.New(`^([1-9][0-9]*)\.(0|[1-9][0-9]*)(\.(0|[1-9][0-9]*))?([a-z]+[0-9]+)?$`)
   307  var laxGoVersionRE = lazyregexp.New(`^v?(([1-9][0-9]*)\.(0|[1-9][0-9]*))([^0-9].*)$`)
   308  
   309  // Toolchains must be named beginning with `go1`,
   310  // like "go1.20.3" or "go1.20.3-gccgo". As a special case, "default" is also permitted.
   311  var ToolchainRE = lazyregexp.New(`^default$|^go1($|\.)`)
   312  
   313  func (f *File) add(errs *ErrorList, block *LineBlock, line *Line, verb string, args []string, fix VersionFixer, strict bool) {
   314  	// If strict is false, this module is a dependency.
   315  	// We ignore all unknown directives as well as main-module-only
   316  	// directives like replace and exclude. It will work better for
   317  	// forward compatibility if we can depend on modules that have unknown
   318  	// statements (presumed relevant only when acting as the main module)
   319  	// and simply ignore those statements.
   320  	if !strict {
   321  		switch verb {
   322  		case "go", "module", "retract", "require":
   323  			// want these even for dependency go.mods
   324  		default:
   325  			return
   326  		}
   327  	}
   328  
   329  	wrapModPathError := func(modPath string, err error) {
   330  		*errs = append(*errs, Error{
   331  			Filename: f.Syntax.Name,
   332  			Pos:      line.Start,
   333  			ModPath:  modPath,
   334  			Verb:     verb,
   335  			Err:      err,
   336  		})
   337  	}
   338  	wrapError := func(err error) {
   339  		*errs = append(*errs, Error{
   340  			Filename: f.Syntax.Name,
   341  			Pos:      line.Start,
   342  			Err:      err,
   343  		})
   344  	}
   345  	errorf := func(format string, args ...interface{}) {
   346  		wrapError(fmt.Errorf(format, args...))
   347  	}
   348  
   349  	switch verb {
   350  	default:
   351  		errorf("unknown directive: %s", verb)
   352  
   353  	case "go":
   354  		if f.Go != nil {
   355  			errorf("repeated go statement")
   356  			return
   357  		}
   358  		if len(args) != 1 {
   359  			errorf("go directive expects exactly one argument")
   360  			return
   361  		} else if !GoVersionRE.MatchString(args[0]) {
   362  			fixed := false
   363  			if !strict {
   364  				if m := laxGoVersionRE.FindStringSubmatch(args[0]); m != nil {
   365  					args[0] = m[1]
   366  					fixed = true
   367  				}
   368  			}
   369  			if !fixed {
   370  				errorf("invalid go version '%s': must match format 1.23.0", args[0])
   371  				return
   372  			}
   373  		}
   374  
   375  		f.Go = &Go{Syntax: line}
   376  		f.Go.Version = args[0]
   377  
   378  	case "toolchain":
   379  		if f.Toolchain != nil {
   380  			errorf("repeated toolchain statement")
   381  			return
   382  		}
   383  		if len(args) != 1 {
   384  			errorf("toolchain directive expects exactly one argument")
   385  			return
   386  		} else if strict && !ToolchainRE.MatchString(args[0]) {
   387  			errorf("invalid toolchain version '%s': must match format go1.23.0 or local", args[0])
   388  			return
   389  		}
   390  		f.Toolchain = &Toolchain{Syntax: line}
   391  		f.Toolchain.Name = args[0]
   392  
   393  	case "module":
   394  		if f.Module != nil {
   395  			errorf("repeated module statement")
   396  			return
   397  		}
   398  		deprecated := parseDeprecation(block, line)
   399  		f.Module = &Module{
   400  			Syntax:     line,
   401  			Deprecated: deprecated,
   402  		}
   403  		if len(args) != 1 {
   404  			errorf("usage: module module/path")
   405  			return
   406  		}
   407  		s, err := parseString(&args[0])
   408  		if err != nil {
   409  			errorf("invalid quoted string: %v", err)
   410  			return
   411  		}
   412  		f.Module.Mod = module.Version{Path: s}
   413  
   414  	case "require", "exclude":
   415  		if len(args) != 2 {
   416  			errorf("usage: %s module/path v1.2.3", verb)
   417  			return
   418  		}
   419  		s, err := parseString(&args[0])
   420  		if err != nil {
   421  			errorf("invalid quoted string: %v", err)
   422  			return
   423  		}
   424  		v, err := parseVersion(verb, s, &args[1], fix)
   425  		if err != nil {
   426  			wrapError(err)
   427  			return
   428  		}
   429  		pathMajor, err := modulePathMajor(s)
   430  		if err != nil {
   431  			wrapError(err)
   432  			return
   433  		}
   434  		if err := module.CheckPathMajor(v, pathMajor); err != nil {
   435  			wrapModPathError(s, err)
   436  			return
   437  		}
   438  		if verb == "require" {
   439  			f.Require = append(f.Require, &Require{
   440  				Mod:      module.Version{Path: s, Version: v},
   441  				Syntax:   line,
   442  				Indirect: isIndirect(line),
   443  			})
   444  		} else {
   445  			f.Exclude = append(f.Exclude, &Exclude{
   446  				Mod:    module.Version{Path: s, Version: v},
   447  				Syntax: line,
   448  			})
   449  		}
   450  
   451  	case "replace":
   452  		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
   453  		if wrappederr != nil {
   454  			*errs = append(*errs, *wrappederr)
   455  			return
   456  		}
   457  		f.Replace = append(f.Replace, replace)
   458  
   459  	case "retract":
   460  		rationale := parseDirectiveComment(block, line)
   461  		vi, err := parseVersionInterval(verb, "", &args, dontFixRetract)
   462  		if err != nil {
   463  			if strict {
   464  				wrapError(err)
   465  				return
   466  			} else {
   467  				// Only report errors parsing intervals in the main module. We may
   468  				// support additional syntax in the future, such as open and half-open
   469  				// intervals. Those can't be supported now, because they break the
   470  				// go.mod parser, even in lax mode.
   471  				return
   472  			}
   473  		}
   474  		if len(args) > 0 && strict {
   475  			// In the future, there may be additional information after the version.
   476  			errorf("unexpected token after version: %q", args[0])
   477  			return
   478  		}
   479  		retract := &Retract{
   480  			VersionInterval: vi,
   481  			Rationale:       rationale,
   482  			Syntax:          line,
   483  		}
   484  		f.Retract = append(f.Retract, retract)
   485  	}
   486  }
   487  
   488  func parseReplace(filename string, line *Line, verb string, args []string, fix VersionFixer) (*Replace, *Error) {
   489  	wrapModPathError := func(modPath string, err error) *Error {
   490  		return &Error{
   491  			Filename: filename,
   492  			Pos:      line.Start,
   493  			ModPath:  modPath,
   494  			Verb:     verb,
   495  			Err:      err,
   496  		}
   497  	}
   498  	wrapError := func(err error) *Error {
   499  		return &Error{
   500  			Filename: filename,
   501  			Pos:      line.Start,
   502  			Err:      err,
   503  		}
   504  	}
   505  	errorf := func(format string, args ...interface{}) *Error {
   506  		return wrapError(fmt.Errorf(format, args...))
   507  	}
   508  
   509  	arrow := 2
   510  	if len(args) >= 2 && args[1] == "=>" {
   511  		arrow = 1
   512  	}
   513  	if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
   514  		return nil, errorf("usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory", verb, verb)
   515  	}
   516  	s, err := parseString(&args[0])
   517  	if err != nil {
   518  		return nil, errorf("invalid quoted string: %v", err)
   519  	}
   520  	pathMajor, err := modulePathMajor(s)
   521  	if err != nil {
   522  		return nil, wrapModPathError(s, err)
   523  
   524  	}
   525  	var v string
   526  	if arrow == 2 {
   527  		v, err = parseVersion(verb, s, &args[1], fix)
   528  		if err != nil {
   529  			return nil, wrapError(err)
   530  		}
   531  		if err := module.CheckPathMajor(v, pathMajor); err != nil {
   532  			return nil, wrapModPathError(s, err)
   533  		}
   534  	}
   535  	ns, err := parseString(&args[arrow+1])
   536  	if err != nil {
   537  		return nil, errorf("invalid quoted string: %v", err)
   538  	}
   539  	nv := ""
   540  	if len(args) == arrow+2 {
   541  		if !IsDirectoryPath(ns) {
   542  			if strings.Contains(ns, "@") {
   543  				return nil, errorf("replacement module must match format 'path version', not 'path@version'")
   544  			}
   545  			return nil, errorf("replacement module without version must be directory path (rooted or starting with . or ..)")
   546  		}
   547  		if filepath.Separator == '/' && strings.Contains(ns, `\`) {
   548  			return nil, errorf("replacement directory appears to be Windows path (on a non-windows system)")
   549  		}
   550  	}
   551  	if len(args) == arrow+3 {
   552  		nv, err = parseVersion(verb, ns, &args[arrow+2], fix)
   553  		if err != nil {
   554  			return nil, wrapError(err)
   555  		}
   556  		if IsDirectoryPath(ns) {
   557  			return nil, errorf("replacement module directory path %q cannot have version", ns)
   558  		}
   559  	}
   560  	return &Replace{
   561  		Old:    module.Version{Path: s, Version: v},
   562  		New:    module.Version{Path: ns, Version: nv},
   563  		Syntax: line,
   564  	}, nil
   565  }
   566  
   567  // fixRetract applies fix to each retract directive in f, appending any errors
   568  // to errs.
   569  //
   570  // Most versions are fixed as we parse the file, but for retract directives,
   571  // the relevant module path is the one specified with the module directive,
   572  // and that might appear at the end of the file (or not at all).
   573  func (f *File) fixRetract(fix VersionFixer, errs *ErrorList) {
   574  	if fix == nil {
   575  		return
   576  	}
   577  	path := ""
   578  	if f.Module != nil {
   579  		path = f.Module.Mod.Path
   580  	}
   581  	var r *Retract
   582  	wrapError := func(err error) {
   583  		*errs = append(*errs, Error{
   584  			Filename: f.Syntax.Name,
   585  			Pos:      r.Syntax.Start,
   586  			Err:      err,
   587  		})
   588  	}
   589  
   590  	for _, r = range f.Retract {
   591  		if path == "" {
   592  			wrapError(errors.New("no module directive found, so retract cannot be used"))
   593  			return // only print the first one of these
   594  		}
   595  
   596  		args := r.Syntax.Token
   597  		if args[0] == "retract" {
   598  			args = args[1:]
   599  		}
   600  		vi, err := parseVersionInterval("retract", path, &args, fix)
   601  		if err != nil {
   602  			wrapError(err)
   603  		}
   604  		r.VersionInterval = vi
   605  	}
   606  }
   607  
   608  func (f *WorkFile) add(errs *ErrorList, line *Line, verb string, args []string, fix VersionFixer) {
   609  	wrapError := func(err error) {
   610  		*errs = append(*errs, Error{
   611  			Filename: f.Syntax.Name,
   612  			Pos:      line.Start,
   613  			Err:      err,
   614  		})
   615  	}
   616  	errorf := func(format string, args ...interface{}) {
   617  		wrapError(fmt.Errorf(format, args...))
   618  	}
   619  
   620  	switch verb {
   621  	default:
   622  		errorf("unknown directive: %s", verb)
   623  
   624  	case "go":
   625  		if f.Go != nil {
   626  			errorf("repeated go statement")
   627  			return
   628  		}
   629  		if len(args) != 1 {
   630  			errorf("go directive expects exactly one argument")
   631  			return
   632  		} else if !GoVersionRE.MatchString(args[0]) {
   633  			errorf("invalid go version '%s': must match format 1.23", args[0])
   634  			return
   635  		}
   636  
   637  		f.Go = &Go{Syntax: line}
   638  		f.Go.Version = args[0]
   639  
   640  	case "toolchain":
   641  		if f.Toolchain != nil {
   642  			errorf("repeated toolchain statement")
   643  			return
   644  		}
   645  		if len(args) != 1 {
   646  			errorf("toolchain directive expects exactly one argument")
   647  			return
   648  		} else if !ToolchainRE.MatchString(args[0]) {
   649  			errorf("invalid toolchain version '%s': must match format go1.23 or local", args[0])
   650  			return
   651  		}
   652  
   653  		f.Toolchain = &Toolchain{Syntax: line}
   654  		f.Toolchain.Name = args[0]
   655  
   656  	case "use":
   657  		if len(args) != 1 {
   658  			errorf("usage: %s local/dir", verb)
   659  			return
   660  		}
   661  		s, err := parseString(&args[0])
   662  		if err != nil {
   663  			errorf("invalid quoted string: %v", err)
   664  			return
   665  		}
   666  		f.Use = append(f.Use, &Use{
   667  			Path:   s,
   668  			Syntax: line,
   669  		})
   670  
   671  	case "replace":
   672  		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
   673  		if wrappederr != nil {
   674  			*errs = append(*errs, *wrappederr)
   675  			return
   676  		}
   677  		f.Replace = append(f.Replace, replace)
   678  	}
   679  }
   680  
   681  // IsDirectoryPath reports whether the given path should be interpreted as a directory path.
   682  // Just like on the go command line, relative paths starting with a '.' or '..' path component
   683  // and rooted paths are directory paths; the rest are module paths.
   684  func IsDirectoryPath(ns string) bool {
   685  	// Because go.mod files can move from one system to another,
   686  	// we check all known path syntaxes, both Unix and Windows.
   687  	return ns == "." || strings.HasPrefix(ns, "./") || strings.HasPrefix(ns, `.\`) ||
   688  		ns == ".." || strings.HasPrefix(ns, "../") || strings.HasPrefix(ns, `..\`) ||
   689  		strings.HasPrefix(ns, "/") || strings.HasPrefix(ns, `\`) ||
   690  		len(ns) >= 2 && ('A' <= ns[0] && ns[0] <= 'Z' || 'a' <= ns[0] && ns[0] <= 'z') && ns[1] == ':'
   691  }
   692  
   693  // MustQuote reports whether s must be quoted in order to appear as
   694  // a single token in a go.mod line.
   695  func MustQuote(s string) bool {
   696  	for _, r := range s {
   697  		switch r {
   698  		case ' ', '"', '\'', '`':
   699  			return true
   700  
   701  		case '(', ')', '[', ']', '{', '}', ',':
   702  			if len(s) > 1 {
   703  				return true
   704  			}
   705  
   706  		default:
   707  			if !unicode.IsPrint(r) {
   708  				return true
   709  			}
   710  		}
   711  	}
   712  	return s == "" || strings.Contains(s, "//") || strings.Contains(s, "/*")
   713  }
   714  
   715  // AutoQuote returns s or, if quoting is required for s to appear in a go.mod,
   716  // the quotation of s.
   717  func AutoQuote(s string) string {
   718  	if MustQuote(s) {
   719  		return strconv.Quote(s)
   720  	}
   721  	return s
   722  }
   723  
   724  func parseVersionInterval(verb string, path string, args *[]string, fix VersionFixer) (VersionInterval, error) {
   725  	toks := *args
   726  	if len(toks) == 0 || toks[0] == "(" {
   727  		return VersionInterval{}, fmt.Errorf("expected '[' or version")
   728  	}
   729  	if toks[0] != "[" {
   730  		v, err := parseVersion(verb, path, &toks[0], fix)
   731  		if err != nil {
   732  			return VersionInterval{}, err
   733  		}
   734  		*args = toks[1:]
   735  		return VersionInterval{Low: v, High: v}, nil
   736  	}
   737  	toks = toks[1:]
   738  
   739  	if len(toks) == 0 {
   740  		return VersionInterval{}, fmt.Errorf("expected version after '['")
   741  	}
   742  	low, err := parseVersion(verb, path, &toks[0], fix)
   743  	if err != nil {
   744  		return VersionInterval{}, err
   745  	}
   746  	toks = toks[1:]
   747  
   748  	if len(toks) == 0 || toks[0] != "," {
   749  		return VersionInterval{}, fmt.Errorf("expected ',' after version")
   750  	}
   751  	toks = toks[1:]
   752  
   753  	if len(toks) == 0 {
   754  		return VersionInterval{}, fmt.Errorf("expected version after ','")
   755  	}
   756  	high, err := parseVersion(verb, path, &toks[0], fix)
   757  	if err != nil {
   758  		return VersionInterval{}, err
   759  	}
   760  	toks = toks[1:]
   761  
   762  	if len(toks) == 0 || toks[0] != "]" {
   763  		return VersionInterval{}, fmt.Errorf("expected ']' after version")
   764  	}
   765  	toks = toks[1:]
   766  
   767  	*args = toks
   768  	return VersionInterval{Low: low, High: high}, nil
   769  }
   770  
   771  func parseString(s *string) (string, error) {
   772  	t := *s
   773  	if strings.HasPrefix(t, `"`) {
   774  		var err error
   775  		if t, err = strconv.Unquote(t); err != nil {
   776  			return "", err
   777  		}
   778  	} else if strings.ContainsAny(t, "\"'`") {
   779  		// Other quotes are reserved both for possible future expansion
   780  		// and to avoid confusion. For example if someone types 'x'
   781  		// we want that to be a syntax error and not a literal x in literal quotation marks.
   782  		return "", fmt.Errorf("unquoted string cannot contain quote")
   783  	}
   784  	*s = AutoQuote(t)
   785  	return t, nil
   786  }
   787  
   788  var deprecatedRE = lazyregexp.New(`(?s)(?:^|\n\n)Deprecated: *(.*?)(?:$|\n\n)`)
   789  
   790  // parseDeprecation extracts the text of comments on a "module" directive and
   791  // extracts a deprecation message from that.
   792  //
   793  // A deprecation message is contained in a paragraph within a block of comments
   794  // that starts with "Deprecated:" (case sensitive). The message runs until the
   795  // end of the paragraph and does not include the "Deprecated:" prefix. If the
   796  // comment block has multiple paragraphs that start with "Deprecated:",
   797  // parseDeprecation returns the message from the first.
   798  func parseDeprecation(block *LineBlock, line *Line) string {
   799  	text := parseDirectiveComment(block, line)
   800  	m := deprecatedRE.FindStringSubmatch(text)
   801  	if m == nil {
   802  		return ""
   803  	}
   804  	return m[1]
   805  }
   806  
   807  // parseDirectiveComment extracts the text of comments on a directive.
   808  // If the directive's line does not have comments and is part of a block that
   809  // does have comments, the block's comments are used.
   810  func parseDirectiveComment(block *LineBlock, line *Line) string {
   811  	comments := line.Comment()
   812  	if block != nil && len(comments.Before) == 0 && len(comments.Suffix) == 0 {
   813  		comments = block.Comment()
   814  	}
   815  	groups := [][]Comment{comments.Before, comments.Suffix}
   816  	var lines []string
   817  	for _, g := range groups {
   818  		for _, c := range g {
   819  			if !strings.HasPrefix(c.Token, "//") {
   820  				continue // blank line
   821  			}
   822  			lines = append(lines, strings.TrimSpace(strings.TrimPrefix(c.Token, "//")))
   823  		}
   824  	}
   825  	return strings.Join(lines, "\n")
   826  }
   827  
   828  type ErrorList []Error
   829  
   830  func (e ErrorList) Error() string {
   831  	errStrs := make([]string, len(e))
   832  	for i, err := range e {
   833  		errStrs[i] = err.Error()
   834  	}
   835  	return strings.Join(errStrs, "\n")
   836  }
   837  
   838  type Error struct {
   839  	Filename string
   840  	Pos      Position
   841  	Verb     string
   842  	ModPath  string
   843  	Err      error
   844  }
   845  
   846  func (e *Error) Error() string {
   847  	var pos string
   848  	if e.Pos.LineRune > 1 {
   849  		// Don't print LineRune if it's 1 (beginning of line).
   850  		// It's always 1 except in scanner errors, which are rare.
   851  		pos = fmt.Sprintf("%s:%d:%d: ", e.Filename, e.Pos.Line, e.Pos.LineRune)
   852  	} else if e.Pos.Line > 0 {
   853  		pos = fmt.Sprintf("%s:%d: ", e.Filename, e.Pos.Line)
   854  	} else if e.Filename != "" {
   855  		pos = fmt.Sprintf("%s: ", e.Filename)
   856  	}
   857  
   858  	var directive string
   859  	if e.ModPath != "" {
   860  		directive = fmt.Sprintf("%s %s: ", e.Verb, e.ModPath)
   861  	} else if e.Verb != "" {
   862  		directive = fmt.Sprintf("%s: ", e.Verb)
   863  	}
   864  
   865  	return pos + directive + e.Err.Error()
   866  }
   867  
   868  func (e *Error) Unwrap() error { return e.Err }
   869  
   870  func parseVersion(verb string, path string, s *string, fix VersionFixer) (string, error) {
   871  	t, err := parseString(s)
   872  	if err != nil {
   873  		return "", &Error{
   874  			Verb:    verb,
   875  			ModPath: path,
   876  			Err: &module.InvalidVersionError{
   877  				Version: *s,
   878  				Err:     err,
   879  			},
   880  		}
   881  	}
   882  	if fix != nil {
   883  		fixed, err := fix(path, t)
   884  		if err != nil {
   885  			if err, ok := err.(*module.ModuleError); ok {
   886  				return "", &Error{
   887  					Verb:    verb,
   888  					ModPath: path,
   889  					Err:     err.Err,
   890  				}
   891  			}
   892  			return "", err
   893  		}
   894  		t = fixed
   895  	} else {
   896  		cv := module.CanonicalVersion(t)
   897  		if cv == "" {
   898  			return "", &Error{
   899  				Verb:    verb,
   900  				ModPath: path,
   901  				Err: &module.InvalidVersionError{
   902  					Version: t,
   903  					Err:     errors.New("must be of the form v1.2.3"),
   904  				},
   905  			}
   906  		}
   907  		t = cv
   908  	}
   909  	*s = t
   910  	return *s, nil
   911  }
   912  
   913  func modulePathMajor(path string) (string, error) {
   914  	_, major, ok := module.SplitPathVersion(path)
   915  	if !ok {
   916  		return "", fmt.Errorf("invalid module path")
   917  	}
   918  	return major, nil
   919  }
   920  
   921  func (f *File) Format() ([]byte, error) {
   922  	return Format(f.Syntax), nil
   923  }
   924  
   925  // Cleanup cleans up the file f after any edit operations.
   926  // To avoid quadratic behavior, modifications like [File.DropRequire]
   927  // clear the entry but do not remove it from the slice.
   928  // Cleanup cleans out all the cleared entries.
   929  func (f *File) Cleanup() {
   930  	w := 0
   931  	for _, r := range f.Require {
   932  		if r.Mod.Path != "" {
   933  			f.Require[w] = r
   934  			w++
   935  		}
   936  	}
   937  	f.Require = f.Require[:w]
   938  
   939  	w = 0
   940  	for _, x := range f.Exclude {
   941  		if x.Mod.Path != "" {
   942  			f.Exclude[w] = x
   943  			w++
   944  		}
   945  	}
   946  	f.Exclude = f.Exclude[:w]
   947  
   948  	w = 0
   949  	for _, r := range f.Replace {
   950  		if r.Old.Path != "" {
   951  			f.Replace[w] = r
   952  			w++
   953  		}
   954  	}
   955  	f.Replace = f.Replace[:w]
   956  
   957  	w = 0
   958  	for _, r := range f.Retract {
   959  		if r.Low != "" || r.High != "" {
   960  			f.Retract[w] = r
   961  			w++
   962  		}
   963  	}
   964  	f.Retract = f.Retract[:w]
   965  
   966  	f.Syntax.Cleanup()
   967  }
   968  
   969  func (f *File) AddGoStmt(version string) error {
   970  	if !GoVersionRE.MatchString(version) {
   971  		return fmt.Errorf("invalid language version %q", version)
   972  	}
   973  	if f.Go == nil {
   974  		var hint Expr
   975  		if f.Module != nil && f.Module.Syntax != nil {
   976  			hint = f.Module.Syntax
   977  		}
   978  		f.Go = &Go{
   979  			Version: version,
   980  			Syntax:  f.Syntax.addLine(hint, "go", version),
   981  		}
   982  	} else {
   983  		f.Go.Version = version
   984  		f.Syntax.updateLine(f.Go.Syntax, "go", version)
   985  	}
   986  	return nil
   987  }
   988  
   989  // DropGoStmt deletes the go statement from the file.
   990  func (f *File) DropGoStmt() {
   991  	if f.Go != nil {
   992  		f.Go.Syntax.markRemoved()
   993  		f.Go = nil
   994  	}
   995  }
   996  
   997  // DropToolchainStmt deletes the toolchain statement from the file.
   998  func (f *File) DropToolchainStmt() {
   999  	if f.Toolchain != nil {
  1000  		f.Toolchain.Syntax.markRemoved()
  1001  		f.Toolchain = nil
  1002  	}
  1003  }
  1004  
  1005  func (f *File) AddToolchainStmt(name string) error {
  1006  	if !ToolchainRE.MatchString(name) {
  1007  		return fmt.Errorf("invalid toolchain name %q", name)
  1008  	}
  1009  	if f.Toolchain == nil {
  1010  		var hint Expr
  1011  		if f.Go != nil && f.Go.Syntax != nil {
  1012  			hint = f.Go.Syntax
  1013  		} else if f.Module != nil && f.Module.Syntax != nil {
  1014  			hint = f.Module.Syntax
  1015  		}
  1016  		f.Toolchain = &Toolchain{
  1017  			Name:   name,
  1018  			Syntax: f.Syntax.addLine(hint, "toolchain", name),
  1019  		}
  1020  	} else {
  1021  		f.Toolchain.Name = name
  1022  		f.Syntax.updateLine(f.Toolchain.Syntax, "toolchain", name)
  1023  	}
  1024  	return nil
  1025  }
  1026  
  1027  // AddRequire sets the first require line for path to version vers,
  1028  // preserving any existing comments for that line and removing all
  1029  // other lines for path.
  1030  //
  1031  // If no line currently exists for path, AddRequire adds a new line
  1032  // at the end of the last require block.
  1033  func (f *File) AddRequire(path, vers string) error {
  1034  	need := true
  1035  	for _, r := range f.Require {
  1036  		if r.Mod.Path == path {
  1037  			if need {
  1038  				r.Mod.Version = vers
  1039  				f.Syntax.updateLine(r.Syntax, "require", AutoQuote(path), vers)
  1040  				need = false
  1041  			} else {
  1042  				r.Syntax.markRemoved()
  1043  				*r = Require{}
  1044  			}
  1045  		}
  1046  	}
  1047  
  1048  	if need {
  1049  		f.AddNewRequire(path, vers, false)
  1050  	}
  1051  	return nil
  1052  }
  1053  
  1054  // AddNewRequire adds a new require line for path at version vers at the end of
  1055  // the last require block, regardless of any existing require lines for path.
  1056  func (f *File) AddNewRequire(path, vers string, indirect bool) {
  1057  	line := f.Syntax.addLine(nil, "require", AutoQuote(path), vers)
  1058  	r := &Require{
  1059  		Mod:    module.Version{Path: path, Version: vers},
  1060  		Syntax: line,
  1061  	}
  1062  	r.setIndirect(indirect)
  1063  	f.Require = append(f.Require, r)
  1064  }
  1065  
  1066  // SetRequire updates the requirements of f to contain exactly req, preserving
  1067  // the existing block structure and line comment contents (except for 'indirect'
  1068  // markings) for the first requirement on each named module path.
  1069  //
  1070  // The Syntax field is ignored for the requirements in req.
  1071  //
  1072  // Any requirements not already present in the file are added to the block
  1073  // containing the last require line.
  1074  //
  1075  // The requirements in req must specify at most one distinct version for each
  1076  // module path.
  1077  //
  1078  // If any existing requirements may be removed, the caller should call
  1079  // [File.Cleanup] after all edits are complete.
  1080  func (f *File) SetRequire(req []*Require) {
  1081  	type elem struct {
  1082  		version  string
  1083  		indirect bool
  1084  	}
  1085  	need := make(map[string]elem)
  1086  	for _, r := range req {
  1087  		if prev, dup := need[r.Mod.Path]; dup && prev.version != r.Mod.Version {
  1088  			panic(fmt.Errorf("SetRequire called with conflicting versions for path %s (%s and %s)", r.Mod.Path, prev.version, r.Mod.Version))
  1089  		}
  1090  		need[r.Mod.Path] = elem{r.Mod.Version, r.Indirect}
  1091  	}
  1092  
  1093  	// Update or delete the existing Require entries to preserve
  1094  	// only the first for each module path in req.
  1095  	for _, r := range f.Require {
  1096  		e, ok := need[r.Mod.Path]
  1097  		if ok {
  1098  			r.setVersion(e.version)
  1099  			r.setIndirect(e.indirect)
  1100  		} else {
  1101  			r.markRemoved()
  1102  		}
  1103  		delete(need, r.Mod.Path)
  1104  	}
  1105  
  1106  	// Add new entries in the last block of the file for any paths that weren't
  1107  	// already present.
  1108  	//
  1109  	// This step is nondeterministic, but the final result will be deterministic
  1110  	// because we will sort the block.
  1111  	for path, e := range need {
  1112  		f.AddNewRequire(path, e.version, e.indirect)
  1113  	}
  1114  
  1115  	f.SortBlocks()
  1116  }
  1117  
  1118  // SetRequireSeparateIndirect updates the requirements of f to contain the given
  1119  // requirements. Comment contents (except for 'indirect' markings) are retained
  1120  // from the first existing requirement for each module path. Like SetRequire,
  1121  // SetRequireSeparateIndirect adds requirements for new paths in req,
  1122  // updates the version and "// indirect" comment on existing requirements,
  1123  // and deletes requirements on paths not in req. Existing duplicate requirements
  1124  // are deleted.
  1125  //
  1126  // As its name suggests, SetRequireSeparateIndirect puts direct and indirect
  1127  // requirements into two separate blocks, one containing only direct
  1128  // requirements, and the other containing only indirect requirements.
  1129  // SetRequireSeparateIndirect may move requirements between these two blocks
  1130  // when their indirect markings change. However, SetRequireSeparateIndirect
  1131  // won't move requirements from other blocks, especially blocks with comments.
  1132  //
  1133  // If the file initially has one uncommented block of requirements,
  1134  // SetRequireSeparateIndirect will split it into a direct-only and indirect-only
  1135  // block. This aids in the transition to separate blocks.
  1136  func (f *File) SetRequireSeparateIndirect(req []*Require) {
  1137  	// hasComments returns whether a line or block has comments
  1138  	// other than "indirect".
  1139  	hasComments := func(c Comments) bool {
  1140  		return len(c.Before) > 0 || len(c.After) > 0 || len(c.Suffix) > 1 ||
  1141  			(len(c.Suffix) == 1 &&
  1142  				strings.TrimSpace(strings.TrimPrefix(c.Suffix[0].Token, string(slashSlash))) != "indirect")
  1143  	}
  1144  
  1145  	// moveReq adds r to block. If r was in another block, moveReq deletes
  1146  	// it from that block and transfers its comments.
  1147  	moveReq := func(r *Require, block *LineBlock) {
  1148  		var line *Line
  1149  		if r.Syntax == nil {
  1150  			line = &Line{Token: []string{AutoQuote(r.Mod.Path), r.Mod.Version}}
  1151  			r.Syntax = line
  1152  			if r.Indirect {
  1153  				r.setIndirect(true)
  1154  			}
  1155  		} else {
  1156  			line = new(Line)
  1157  			*line = *r.Syntax
  1158  			if !line.InBlock && len(line.Token) > 0 && line.Token[0] == "require" {
  1159  				line.Token = line.Token[1:]
  1160  			}
  1161  			r.Syntax.Token = nil // Cleanup will delete the old line.
  1162  			r.Syntax = line
  1163  		}
  1164  		line.InBlock = true
  1165  		block.Line = append(block.Line, line)
  1166  	}
  1167  
  1168  	// Examine existing require lines and blocks.
  1169  	var (
  1170  		// We may insert new requirements into the last uncommented
  1171  		// direct-only and indirect-only blocks. We may also move requirements
  1172  		// to the opposite block if their indirect markings change.
  1173  		lastDirectIndex   = -1
  1174  		lastIndirectIndex = -1
  1175  
  1176  		// If there are no direct-only or indirect-only blocks, a new block may
  1177  		// be inserted after the last require line or block.
  1178  		lastRequireIndex = -1
  1179  
  1180  		// If there's only one require line or block, and it's uncommented,
  1181  		// we'll move its requirements to the direct-only or indirect-only blocks.
  1182  		requireLineOrBlockCount = 0
  1183  
  1184  		// Track the block each requirement belongs to (if any) so we can
  1185  		// move them later.
  1186  		lineToBlock = make(map[*Line]*LineBlock)
  1187  	)
  1188  	for i, stmt := range f.Syntax.Stmt {
  1189  		switch stmt := stmt.(type) {
  1190  		case *Line:
  1191  			if len(stmt.Token) == 0 || stmt.Token[0] != "require" {
  1192  				continue
  1193  			}
  1194  			lastRequireIndex = i
  1195  			requireLineOrBlockCount++
  1196  			if !hasComments(stmt.Comments) {
  1197  				if isIndirect(stmt) {
  1198  					lastIndirectIndex = i
  1199  				} else {
  1200  					lastDirectIndex = i
  1201  				}
  1202  			}
  1203  
  1204  		case *LineBlock:
  1205  			if len(stmt.Token) == 0 || stmt.Token[0] != "require" {
  1206  				continue
  1207  			}
  1208  			lastRequireIndex = i
  1209  			requireLineOrBlockCount++
  1210  			allDirect := len(stmt.Line) > 0 && !hasComments(stmt.Comments)
  1211  			allIndirect := len(stmt.Line) > 0 && !hasComments(stmt.Comments)
  1212  			for _, line := range stmt.Line {
  1213  				lineToBlock[line] = stmt
  1214  				if hasComments(line.Comments) {
  1215  					allDirect = false
  1216  					allIndirect = false
  1217  				} else if isIndirect(line) {
  1218  					allDirect = false
  1219  				} else {
  1220  					allIndirect = false
  1221  				}
  1222  			}
  1223  			if allDirect {
  1224  				lastDirectIndex = i
  1225  			}
  1226  			if allIndirect {
  1227  				lastIndirectIndex = i
  1228  			}
  1229  		}
  1230  	}
  1231  
  1232  	oneFlatUncommentedBlock := requireLineOrBlockCount == 1 &&
  1233  		!hasComments(*f.Syntax.Stmt[lastRequireIndex].Comment())
  1234  
  1235  	// Create direct and indirect blocks if needed. Convert lines into blocks
  1236  	// if needed. If we end up with an empty block or a one-line block,
  1237  	// Cleanup will delete it or convert it to a line later.
  1238  	insertBlock := func(i int) *LineBlock {
  1239  		block := &LineBlock{Token: []string{"require"}}
  1240  		f.Syntax.Stmt = append(f.Syntax.Stmt, nil)
  1241  		copy(f.Syntax.Stmt[i+1:], f.Syntax.Stmt[i:])
  1242  		f.Syntax.Stmt[i] = block
  1243  		return block
  1244  	}
  1245  
  1246  	ensureBlock := func(i int) *LineBlock {
  1247  		switch stmt := f.Syntax.Stmt[i].(type) {
  1248  		case *LineBlock:
  1249  			return stmt
  1250  		case *Line:
  1251  			block := &LineBlock{
  1252  				Token: []string{"require"},
  1253  				Line:  []*Line{stmt},
  1254  			}
  1255  			stmt.Token = stmt.Token[1:] // remove "require"
  1256  			stmt.InBlock = true
  1257  			f.Syntax.Stmt[i] = block
  1258  			return block
  1259  		default:
  1260  			panic(fmt.Sprintf("unexpected statement: %v", stmt))
  1261  		}
  1262  	}
  1263  
  1264  	var lastDirectBlock *LineBlock
  1265  	if lastDirectIndex < 0 {
  1266  		if lastIndirectIndex >= 0 {
  1267  			lastDirectIndex = lastIndirectIndex
  1268  			lastIndirectIndex++
  1269  		} else if lastRequireIndex >= 0 {
  1270  			lastDirectIndex = lastRequireIndex + 1
  1271  		} else {
  1272  			lastDirectIndex = len(f.Syntax.Stmt)
  1273  		}
  1274  		lastDirectBlock = insertBlock(lastDirectIndex)
  1275  	} else {
  1276  		lastDirectBlock = ensureBlock(lastDirectIndex)
  1277  	}
  1278  
  1279  	var lastIndirectBlock *LineBlock
  1280  	if lastIndirectIndex < 0 {
  1281  		lastIndirectIndex = lastDirectIndex + 1
  1282  		lastIndirectBlock = insertBlock(lastIndirectIndex)
  1283  	} else {
  1284  		lastIndirectBlock = ensureBlock(lastIndirectIndex)
  1285  	}
  1286  
  1287  	// Delete requirements we don't want anymore.
  1288  	// Update versions and indirect comments on requirements we want to keep.
  1289  	// If a requirement is in last{Direct,Indirect}Block with the wrong
  1290  	// indirect marking after this, or if the requirement is in an single
  1291  	// uncommented mixed block (oneFlatUncommentedBlock), move it to the
  1292  	// correct block.
  1293  	//
  1294  	// Some blocks may be empty after this. Cleanup will remove them.
  1295  	need := make(map[string]*Require)
  1296  	for _, r := range req {
  1297  		need[r.Mod.Path] = r
  1298  	}
  1299  	have := make(map[string]*Require)
  1300  	for _, r := range f.Require {
  1301  		path := r.Mod.Path
  1302  		if need[path] == nil || have[path] != nil {
  1303  			// Requirement not needed, or duplicate requirement. Delete.
  1304  			r.markRemoved()
  1305  			continue
  1306  		}
  1307  		have[r.Mod.Path] = r
  1308  		r.setVersion(need[path].Mod.Version)
  1309  		r.setIndirect(need[path].Indirect)
  1310  		if need[path].Indirect &&
  1311  			(oneFlatUncommentedBlock || lineToBlock[r.Syntax] == lastDirectBlock) {
  1312  			moveReq(r, lastIndirectBlock)
  1313  		} else if !need[path].Indirect &&
  1314  			(oneFlatUncommentedBlock || lineToBlock[r.Syntax] == lastIndirectBlock) {
  1315  			moveReq(r, lastDirectBlock)
  1316  		}
  1317  	}
  1318  
  1319  	// Add new requirements.
  1320  	for path, r := range need {
  1321  		if have[path] == nil {
  1322  			if r.Indirect {
  1323  				moveReq(r, lastIndirectBlock)
  1324  			} else {
  1325  				moveReq(r, lastDirectBlock)
  1326  			}
  1327  			f.Require = append(f.Require, r)
  1328  		}
  1329  	}
  1330  
  1331  	f.SortBlocks()
  1332  }
  1333  
  1334  func (f *File) DropRequire(path string) error {
  1335  	for _, r := range f.Require {
  1336  		if r.Mod.Path == path {
  1337  			r.Syntax.markRemoved()
  1338  			*r = Require{}
  1339  		}
  1340  	}
  1341  	return nil
  1342  }
  1343  
  1344  // AddExclude adds a exclude statement to the mod file. Errors if the provided
  1345  // version is not a canonical version string
  1346  func (f *File) AddExclude(path, vers string) error {
  1347  	if err := checkCanonicalVersion(path, vers); err != nil {
  1348  		return err
  1349  	}
  1350  
  1351  	var hint *Line
  1352  	for _, x := range f.Exclude {
  1353  		if x.Mod.Path == path && x.Mod.Version == vers {
  1354  			return nil
  1355  		}
  1356  		if x.Mod.Path == path {
  1357  			hint = x.Syntax
  1358  		}
  1359  	}
  1360  
  1361  	f.Exclude = append(f.Exclude, &Exclude{Mod: module.Version{Path: path, Version: vers}, Syntax: f.Syntax.addLine(hint, "exclude", AutoQuote(path), vers)})
  1362  	return nil
  1363  }
  1364  
  1365  func (f *File) DropExclude(path, vers string) error {
  1366  	for _, x := range f.Exclude {
  1367  		if x.Mod.Path == path && x.Mod.Version == vers {
  1368  			x.Syntax.markRemoved()
  1369  			*x = Exclude{}
  1370  		}
  1371  	}
  1372  	return nil
  1373  }
  1374  
  1375  func (f *File) AddReplace(oldPath, oldVers, newPath, newVers string) error {
  1376  	return addReplace(f.Syntax, &f.Replace, oldPath, oldVers, newPath, newVers)
  1377  }
  1378  
  1379  func addReplace(syntax *FileSyntax, replace *[]*Replace, oldPath, oldVers, newPath, newVers string) error {
  1380  	need := true
  1381  	old := module.Version{Path: oldPath, Version: oldVers}
  1382  	new := module.Version{Path: newPath, Version: newVers}
  1383  	tokens := []string{"replace", AutoQuote(oldPath)}
  1384  	if oldVers != "" {
  1385  		tokens = append(tokens, oldVers)
  1386  	}
  1387  	tokens = append(tokens, "=>", AutoQuote(newPath))
  1388  	if newVers != "" {
  1389  		tokens = append(tokens, newVers)
  1390  	}
  1391  
  1392  	var hint *Line
  1393  	for _, r := range *replace {
  1394  		if r.Old.Path == oldPath && (oldVers == "" || r.Old.Version == oldVers) {
  1395  			if need {
  1396  				// Found replacement for old; update to use new.
  1397  				r.New = new
  1398  				syntax.updateLine(r.Syntax, tokens...)
  1399  				need = false
  1400  				continue
  1401  			}
  1402  			// Already added; delete other replacements for same.
  1403  			r.Syntax.markRemoved()
  1404  			*r = Replace{}
  1405  		}
  1406  		if r.Old.Path == oldPath {
  1407  			hint = r.Syntax
  1408  		}
  1409  	}
  1410  	if need {
  1411  		*replace = append(*replace, &Replace{Old: old, New: new, Syntax: syntax.addLine(hint, tokens...)})
  1412  	}
  1413  	return nil
  1414  }
  1415  
  1416  func (f *File) DropReplace(oldPath, oldVers string) error {
  1417  	for _, r := range f.Replace {
  1418  		if r.Old.Path == oldPath && r.Old.Version == oldVers {
  1419  			r.Syntax.markRemoved()
  1420  			*r = Replace{}
  1421  		}
  1422  	}
  1423  	return nil
  1424  }
  1425  
  1426  // AddRetract adds a retract statement to the mod file. Errors if the provided
  1427  // version interval does not consist of canonical version strings
  1428  func (f *File) AddRetract(vi VersionInterval, rationale string) error {
  1429  	var path string
  1430  	if f.Module != nil {
  1431  		path = f.Module.Mod.Path
  1432  	}
  1433  	if err := checkCanonicalVersion(path, vi.High); err != nil {
  1434  		return err
  1435  	}
  1436  	if err := checkCanonicalVersion(path, vi.Low); err != nil {
  1437  		return err
  1438  	}
  1439  
  1440  	r := &Retract{
  1441  		VersionInterval: vi,
  1442  	}
  1443  	if vi.Low == vi.High {
  1444  		r.Syntax = f.Syntax.addLine(nil, "retract", AutoQuote(vi.Low))
  1445  	} else {
  1446  		r.Syntax = f.Syntax.addLine(nil, "retract", "[", AutoQuote(vi.Low), ",", AutoQuote(vi.High), "]")
  1447  	}
  1448  	if rationale != "" {
  1449  		for _, line := range strings.Split(rationale, "\n") {
  1450  			com := Comment{Token: "// " + line}
  1451  			r.Syntax.Comment().Before = append(r.Syntax.Comment().Before, com)
  1452  		}
  1453  	}
  1454  	return nil
  1455  }
  1456  
  1457  func (f *File) DropRetract(vi VersionInterval) error {
  1458  	for _, r := range f.Retract {
  1459  		if r.VersionInterval == vi {
  1460  			r.Syntax.markRemoved()
  1461  			*r = Retract{}
  1462  		}
  1463  	}
  1464  	return nil
  1465  }
  1466  
  1467  func (f *File) SortBlocks() {
  1468  	f.removeDups() // otherwise sorting is unsafe
  1469  
  1470  	// semanticSortForExcludeVersionV is the Go version (plus leading "v") at which
  1471  	// lines in exclude blocks start to use semantic sort instead of lexicographic sort.
  1472  	// See go.dev/issue/60028.
  1473  	const semanticSortForExcludeVersionV = "v1.21"
  1474  	useSemanticSortForExclude := f.Go != nil && semver.Compare("v"+f.Go.Version, semanticSortForExcludeVersionV) >= 0
  1475  
  1476  	for _, stmt := range f.Syntax.Stmt {
  1477  		block, ok := stmt.(*LineBlock)
  1478  		if !ok {
  1479  			continue
  1480  		}
  1481  		less := lineLess
  1482  		if block.Token[0] == "exclude" && useSemanticSortForExclude {
  1483  			less = lineExcludeLess
  1484  		} else if block.Token[0] == "retract" {
  1485  			less = lineRetractLess
  1486  		}
  1487  		sort.SliceStable(block.Line, func(i, j int) bool {
  1488  			return less(block.Line[i], block.Line[j])
  1489  		})
  1490  	}
  1491  }
  1492  
  1493  // removeDups removes duplicate exclude and replace directives.
  1494  //
  1495  // Earlier exclude directives take priority.
  1496  //
  1497  // Later replace directives take priority.
  1498  //
  1499  // require directives are not de-duplicated. That's left up to higher-level
  1500  // logic (MVS).
  1501  //
  1502  // retract directives are not de-duplicated since comments are
  1503  // meaningful, and versions may be retracted multiple times.
  1504  func (f *File) removeDups() {
  1505  	removeDups(f.Syntax, &f.Exclude, &f.Replace)
  1506  }
  1507  
  1508  func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace) {
  1509  	kill := make(map[*Line]bool)
  1510  
  1511  	// Remove duplicate excludes.
  1512  	if exclude != nil {
  1513  		haveExclude := make(map[module.Version]bool)
  1514  		for _, x := range *exclude {
  1515  			if haveExclude[x.Mod] {
  1516  				kill[x.Syntax] = true
  1517  				continue
  1518  			}
  1519  			haveExclude[x.Mod] = true
  1520  		}
  1521  		var excl []*Exclude
  1522  		for _, x := range *exclude {
  1523  			if !kill[x.Syntax] {
  1524  				excl = append(excl, x)
  1525  			}
  1526  		}
  1527  		*exclude = excl
  1528  	}
  1529  
  1530  	// Remove duplicate replacements.
  1531  	// Later replacements take priority over earlier ones.
  1532  	haveReplace := make(map[module.Version]bool)
  1533  	for i := len(*replace) - 1; i >= 0; i-- {
  1534  		x := (*replace)[i]
  1535  		if haveReplace[x.Old] {
  1536  			kill[x.Syntax] = true
  1537  			continue
  1538  		}
  1539  		haveReplace[x.Old] = true
  1540  	}
  1541  	var repl []*Replace
  1542  	for _, x := range *replace {
  1543  		if !kill[x.Syntax] {
  1544  			repl = append(repl, x)
  1545  		}
  1546  	}
  1547  	*replace = repl
  1548  
  1549  	// Duplicate require and retract directives are not removed.
  1550  
  1551  	// Drop killed statements from the syntax tree.
  1552  	var stmts []Expr
  1553  	for _, stmt := range syntax.Stmt {
  1554  		switch stmt := stmt.(type) {
  1555  		case *Line:
  1556  			if kill[stmt] {
  1557  				continue
  1558  			}
  1559  		case *LineBlock:
  1560  			var lines []*Line
  1561  			for _, line := range stmt.Line {
  1562  				if !kill[line] {
  1563  					lines = append(lines, line)
  1564  				}
  1565  			}
  1566  			stmt.Line = lines
  1567  			if len(lines) == 0 {
  1568  				continue
  1569  			}
  1570  		}
  1571  		stmts = append(stmts, stmt)
  1572  	}
  1573  	syntax.Stmt = stmts
  1574  }
  1575  
  1576  // lineLess returns whether li should be sorted before lj. It sorts
  1577  // lexicographically without assigning any special meaning to tokens.
  1578  func lineLess(li, lj *Line) bool {
  1579  	for k := 0; k < len(li.Token) && k < len(lj.Token); k++ {
  1580  		if li.Token[k] != lj.Token[k] {
  1581  			return li.Token[k] < lj.Token[k]
  1582  		}
  1583  	}
  1584  	return len(li.Token) < len(lj.Token)
  1585  }
  1586  
  1587  // lineExcludeLess reports whether li should be sorted before lj for lines in
  1588  // an "exclude" block.
  1589  func lineExcludeLess(li, lj *Line) bool {
  1590  	if len(li.Token) != 2 || len(lj.Token) != 2 {
  1591  		// Not a known exclude specification.
  1592  		// Fall back to sorting lexicographically.
  1593  		return lineLess(li, lj)
  1594  	}
  1595  	// An exclude specification has two tokens: ModulePath and Version.
  1596  	// Compare module path by string order and version by semver rules.
  1597  	if pi, pj := li.Token[0], lj.Token[0]; pi != pj {
  1598  		return pi < pj
  1599  	}
  1600  	return semver.Compare(li.Token[1], lj.Token[1]) < 0
  1601  }
  1602  
  1603  // lineRetractLess returns whether li should be sorted before lj for lines in
  1604  // a "retract" block. It treats each line as a version interval. Single versions
  1605  // are compared as if they were intervals with the same low and high version.
  1606  // Intervals are sorted in descending order, first by low version, then by
  1607  // high version, using semver.Compare.
  1608  func lineRetractLess(li, lj *Line) bool {
  1609  	interval := func(l *Line) VersionInterval {
  1610  		if len(l.Token) == 1 {
  1611  			return VersionInterval{Low: l.Token[0], High: l.Token[0]}
  1612  		} else if len(l.Token) == 5 && l.Token[0] == "[" && l.Token[2] == "," && l.Token[4] == "]" {
  1613  			return VersionInterval{Low: l.Token[1], High: l.Token[3]}
  1614  		} else {
  1615  			// Line in unknown format. Treat as an invalid version.
  1616  			return VersionInterval{}
  1617  		}
  1618  	}
  1619  	vii := interval(li)
  1620  	vij := interval(lj)
  1621  	if cmp := semver.Compare(vii.Low, vij.Low); cmp != 0 {
  1622  		return cmp > 0
  1623  	}
  1624  	return semver.Compare(vii.High, vij.High) > 0
  1625  }
  1626  
  1627  // checkCanonicalVersion returns a non-nil error if vers is not a canonical
  1628  // version string or does not match the major version of path.
  1629  //
  1630  // If path is non-empty, the error text suggests a format with a major version
  1631  // corresponding to the path.
  1632  func checkCanonicalVersion(path, vers string) error {
  1633  	_, pathMajor, pathMajorOk := module.SplitPathVersion(path)
  1634  
  1635  	if vers == "" || vers != module.CanonicalVersion(vers) {
  1636  		if pathMajor == "" {
  1637  			return &module.InvalidVersionError{
  1638  				Version: vers,
  1639  				Err:     fmt.Errorf("must be of the form v1.2.3"),
  1640  			}
  1641  		}
  1642  		return &module.InvalidVersionError{
  1643  			Version: vers,
  1644  			Err:     fmt.Errorf("must be of the form %s.2.3", module.PathMajorPrefix(pathMajor)),
  1645  		}
  1646  	}
  1647  
  1648  	if pathMajorOk {
  1649  		if err := module.CheckPathMajor(vers, pathMajor); err != nil {
  1650  			if pathMajor == "" {
  1651  				// In this context, the user probably wrote "v2.3.4" when they meant
  1652  				// "v2.3.4+incompatible". Suggest that instead of "v0 or v1".
  1653  				return &module.InvalidVersionError{
  1654  					Version: vers,
  1655  					Err:     fmt.Errorf("should be %s+incompatible (or module %s/%v)", vers, path, semver.Major(vers)),
  1656  				}
  1657  			}
  1658  			return err
  1659  		}
  1660  	}
  1661  
  1662  	return nil
  1663  }
  1664
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