imports.go

Documentation: cmd/vendor/golang.org/x/tools/internal/facts

     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 facts
     6  
     7  import (
     8  	"go/types"
     9  
    10  	"golang.org/x/tools/internal/aliases"
    11  )
    12  
    13  // importMap computes the import map for a package by traversing the
    14  // entire exported API each of its imports.
    15  //
    16  // This is a workaround for the fact that we cannot access the map used
    17  // internally by the types.Importer returned by go/importer. The entries
    18  // in this map are the packages and objects that may be relevant to the
    19  // current analysis unit.
    20  //
    21  // Packages in the map that are only indirectly imported may be
    22  // incomplete (!pkg.Complete()).
    23  //
    24  // This function scales very poorly with packages' transitive object
    25  // references, which can be more than a million for each package near
    26  // the top of a large project. (This was a significant contributor to
    27  // #60621.)
    28  // TODO(adonovan): opt: compute this information more efficiently
    29  // by obtaining it from the internals of the gcexportdata decoder.
    30  func importMap(imports []*types.Package) map[string]*types.Package {
    31  	objects := make(map[types.Object]bool)
    32  	typs := make(map[types.Type]bool) // Named and TypeParam
    33  	packages := make(map[string]*types.Package)
    34  
    35  	var addObj func(obj types.Object)
    36  	var addType func(T types.Type)
    37  
    38  	addObj = func(obj types.Object) {
    39  		if !objects[obj] {
    40  			objects[obj] = true
    41  			addType(obj.Type())
    42  			if pkg := obj.Pkg(); pkg != nil {
    43  				packages[pkg.Path()] = pkg
    44  			}
    45  		}
    46  	}
    47  
    48  	addType = func(T types.Type) {
    49  		switch T := T.(type) {
    50  		case *aliases.Alias:
    51  			addType(aliases.Unalias(T))
    52  		case *types.Basic:
    53  			// nop
    54  		case *types.Named:
    55  			// Remove infinite expansions of *types.Named by always looking at the origin.
    56  			// Some named types with type parameters [that will not type check] have
    57  			// infinite expansions:
    58  			//     type N[T any] struct { F *N[N[T]] }
    59  			// importMap() is called on such types when Analyzer.RunDespiteErrors is true.
    60  			T = T.Origin()
    61  			if !typs[T] {
    62  				typs[T] = true
    63  				addObj(T.Obj())
    64  				addType(T.Underlying())
    65  				for i := 0; i < T.NumMethods(); i++ {
    66  					addObj(T.Method(i))
    67  				}
    68  				if tparams := T.TypeParams(); tparams != nil {
    69  					for i := 0; i < tparams.Len(); i++ {
    70  						addType(tparams.At(i))
    71  					}
    72  				}
    73  				if targs := T.TypeArgs(); targs != nil {
    74  					for i := 0; i < targs.Len(); i++ {
    75  						addType(targs.At(i))
    76  					}
    77  				}
    78  			}
    79  		case *types.Pointer:
    80  			addType(T.Elem())
    81  		case *types.Slice:
    82  			addType(T.Elem())
    83  		case *types.Array:
    84  			addType(T.Elem())
    85  		case *types.Chan:
    86  			addType(T.Elem())
    87  		case *types.Map:
    88  			addType(T.Key())
    89  			addType(T.Elem())
    90  		case *types.Signature:
    91  			addType(T.Params())
    92  			addType(T.Results())
    93  			if tparams := T.TypeParams(); tparams != nil {
    94  				for i := 0; i < tparams.Len(); i++ {
    95  					addType(tparams.At(i))
    96  				}
    97  			}
    98  		case *types.Struct:
    99  			for i := 0; i < T.NumFields(); i++ {
   100  				addObj(T.Field(i))
   101  			}
   102  		case *types.Tuple:
   103  			for i := 0; i < T.Len(); i++ {
   104  				addObj(T.At(i))
   105  			}
   106  		case *types.Interface:
   107  			for i := 0; i < T.NumMethods(); i++ {
   108  				addObj(T.Method(i))
   109  			}
   110  			for i := 0; i < T.NumEmbeddeds(); i++ {
   111  				addType(T.EmbeddedType(i)) // walk Embedded for implicits
   112  			}
   113  		case *types.Union:
   114  			for i := 0; i < T.Len(); i++ {
   115  				addType(T.Term(i).Type())
   116  			}
   117  		case *types.TypeParam:
   118  			if !typs[T] {
   119  				typs[T] = true
   120  				addObj(T.Obj())
   121  				addType(T.Constraint())
   122  			}
   123  		}
   124  	}
   125  
   126  	for _, imp := range imports {
   127  		packages[imp.Path()] = imp
   128  
   129  		scope := imp.Scope()
   130  		for _, name := range scope.Names() {
   131  			addObj(scope.Lookup(name))
   132  		}
   133  	}
   134  
   135  	return packages
   136  }
   137
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