support.go

     1  // Copyright 2015 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  // This file implements support functionality for iimport.go.
     6  
     7  package importer
     8  
     9  import (
    10  	"cmd/compile/internal/base"
    11  	"cmd/compile/internal/types2"
    12  	"fmt"
    13  	"go/token"
    14  	"internal/pkgbits"
    15  	"sync"
    16  )
    17  
    18  func assert(p bool) {
    19  	base.Assert(p)
    20  }
    21  
    22  func errorf(format string, args ...interface{}) {
    23  	panic(fmt.Sprintf(format, args...))
    24  }
    25  
    26  const deltaNewFile = -64 // see cmd/compile/internal/gc/bexport.go
    27  
    28  // Synthesize a token.Pos
    29  type fakeFileSet struct {
    30  	fset  *token.FileSet
    31  	files map[string]*token.File
    32  }
    33  
    34  func (s *fakeFileSet) pos(file string, line, column int) token.Pos {
    35  	// TODO(mdempsky): Make use of column.
    36  
    37  	// Since we don't know the set of needed file positions, we
    38  	// reserve maxlines positions per file.
    39  	const maxlines = 64 * 1024
    40  	f := s.files[file]
    41  	if f == nil {
    42  		f = s.fset.AddFile(file, -1, maxlines)
    43  		s.files[file] = f
    44  		// Allocate the fake linebreak indices on first use.
    45  		// TODO(adonovan): opt: save ~512KB using a more complex scheme?
    46  		fakeLinesOnce.Do(func() {
    47  			fakeLines = make([]int, maxlines)
    48  			for i := range fakeLines {
    49  				fakeLines[i] = i
    50  			}
    51  		})
    52  		f.SetLines(fakeLines)
    53  	}
    54  
    55  	if line > maxlines {
    56  		line = 1
    57  	}
    58  
    59  	// Treat the file as if it contained only newlines
    60  	// and column=1: use the line number as the offset.
    61  	return f.Pos(line - 1)
    62  }
    63  
    64  var (
    65  	fakeLines     []int
    66  	fakeLinesOnce sync.Once
    67  )
    68  
    69  func chanDir(d int) types2.ChanDir {
    70  	// tag values must match the constants in cmd/compile/internal/gc/go.go
    71  	switch d {
    72  	case 1 /* Crecv */ :
    73  		return types2.RecvOnly
    74  	case 2 /* Csend */ :
    75  		return types2.SendOnly
    76  	case 3 /* Cboth */ :
    77  		return types2.SendRecv
    78  	default:
    79  		errorf("unexpected channel dir %d", d)
    80  		return 0
    81  	}
    82  }
    83  
    84  var predeclared = []types2.Type{
    85  	// basic types
    86  	types2.Typ[types2.Bool],
    87  	types2.Typ[types2.Int],
    88  	types2.Typ[types2.Int8],
    89  	types2.Typ[types2.Int16],
    90  	types2.Typ[types2.Int32],
    91  	types2.Typ[types2.Int64],
    92  	types2.Typ[types2.Uint],
    93  	types2.Typ[types2.Uint8],
    94  	types2.Typ[types2.Uint16],
    95  	types2.Typ[types2.Uint32],
    96  	types2.Typ[types2.Uint64],
    97  	types2.Typ[types2.Uintptr],
    98  	types2.Typ[types2.Float32],
    99  	types2.Typ[types2.Float64],
   100  	types2.Typ[types2.Complex64],
   101  	types2.Typ[types2.Complex128],
   102  	types2.Typ[types2.String],
   103  
   104  	// basic type aliases
   105  	types2.Universe.Lookup("byte").Type(),
   106  	types2.Universe.Lookup("rune").Type(),
   107  
   108  	// error
   109  	types2.Universe.Lookup("error").Type(),
   110  
   111  	// untyped types
   112  	types2.Typ[types2.UntypedBool],
   113  	types2.Typ[types2.UntypedInt],
   114  	types2.Typ[types2.UntypedRune],
   115  	types2.Typ[types2.UntypedFloat],
   116  	types2.Typ[types2.UntypedComplex],
   117  	types2.Typ[types2.UntypedString],
   118  	types2.Typ[types2.UntypedNil],
   119  
   120  	// package unsafe
   121  	types2.Typ[types2.UnsafePointer],
   122  
   123  	// invalid type
   124  	types2.Typ[types2.Invalid], // only appears in packages with errors
   125  
   126  	// used internally by gc; never used by this package or in .a files
   127  	// not to be confused with the universe any
   128  	anyType{},
   129  
   130  	// comparable
   131  	types2.Universe.Lookup("comparable").Type(),
   132  
   133  	// "any" has special handling: see usage of predeclared.
   134  }
   135  
   136  type anyType struct{}
   137  
   138  func (t anyType) Underlying() types2.Type { return t }
   139  func (t anyType) String() string          { return "any" }
   140  
   141  // See cmd/compile/internal/noder.derivedInfo.
   142  type derivedInfo struct {
   143  	idx    pkgbits.Index
   144  	needed bool
   145  }
   146  
   147  // See cmd/compile/internal/noder.typeInfo.
   148  type typeInfo struct {
   149  	idx     pkgbits.Index
   150  	derived bool
   151  }
   152
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