support.go

Documentation: go/internal/gcimporter

     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 gcimporter
     8  
     9  import (
    10  	"fmt"
    11  	"go/token"
    12  	"go/types"
    13  	"sync"
    14  )
    15  
    16  func errorf(format string, args ...interface{}) {
    17  	panic(fmt.Sprintf(format, args...))
    18  }
    19  
    20  // deltaNewFile is a magic line delta offset indicating a new file.
    21  // We use -64 because it is rare; see issue 20080 and CL 41619.
    22  // -64 is the smallest int that fits in a single byte as a varint.
    23  const deltaNewFile = -64
    24  
    25  // Synthesize a token.Pos
    26  type fakeFileSet struct {
    27  	fset  *token.FileSet
    28  	files map[string]*token.File
    29  }
    30  
    31  func (s *fakeFileSet) pos(file string, line, column int) token.Pos {
    32  	// TODO(mdempsky): Make use of column.
    33  
    34  	// Since we don't know the set of needed file positions, we
    35  	// reserve maxlines positions per file.
    36  	const maxlines = 64 * 1024
    37  	f := s.files[file]
    38  	if f == nil {
    39  		f = s.fset.AddFile(file, -1, maxlines)
    40  		s.files[file] = f
    41  		// Allocate the fake linebreak indices on first use.
    42  		// TODO(adonovan): opt: save ~512KB using a more complex scheme?
    43  		fakeLinesOnce.Do(func() {
    44  			fakeLines = make([]int, maxlines)
    45  			for i := range fakeLines {
    46  				fakeLines[i] = i
    47  			}
    48  		})
    49  		f.SetLines(fakeLines)
    50  	}
    51  
    52  	if line > maxlines {
    53  		line = 1
    54  	}
    55  
    56  	// Treat the file as if it contained only newlines
    57  	// and column=1: use the line number as the offset.
    58  	return f.Pos(line - 1)
    59  }
    60  
    61  var (
    62  	fakeLines     []int
    63  	fakeLinesOnce sync.Once
    64  )
    65  
    66  func chanDir(d int) types.ChanDir {
    67  	// tag values must match the constants in cmd/compile/internal/gc/go.go
    68  	switch d {
    69  	case 1 /* Crecv */ :
    70  		return types.RecvOnly
    71  	case 2 /* Csend */ :
    72  		return types.SendOnly
    73  	case 3 /* Cboth */ :
    74  		return types.SendRecv
    75  	default:
    76  		errorf("unexpected channel dir %d", d)
    77  		return 0
    78  	}
    79  }
    80  
    81  var predeclared = []types.Type{
    82  	// basic types
    83  	types.Typ[types.Bool],
    84  	types.Typ[types.Int],
    85  	types.Typ[types.Int8],
    86  	types.Typ[types.Int16],
    87  	types.Typ[types.Int32],
    88  	types.Typ[types.Int64],
    89  	types.Typ[types.Uint],
    90  	types.Typ[types.Uint8],
    91  	types.Typ[types.Uint16],
    92  	types.Typ[types.Uint32],
    93  	types.Typ[types.Uint64],
    94  	types.Typ[types.Uintptr],
    95  	types.Typ[types.Float32],
    96  	types.Typ[types.Float64],
    97  	types.Typ[types.Complex64],
    98  	types.Typ[types.Complex128],
    99  	types.Typ[types.String],
   100  
   101  	// basic type aliases
   102  	types.Universe.Lookup("byte").Type(),
   103  	types.Universe.Lookup("rune").Type(),
   104  
   105  	// error
   106  	types.Universe.Lookup("error").Type(),
   107  
   108  	// untyped types
   109  	types.Typ[types.UntypedBool],
   110  	types.Typ[types.UntypedInt],
   111  	types.Typ[types.UntypedRune],
   112  	types.Typ[types.UntypedFloat],
   113  	types.Typ[types.UntypedComplex],
   114  	types.Typ[types.UntypedString],
   115  	types.Typ[types.UntypedNil],
   116  
   117  	// package unsafe
   118  	types.Typ[types.UnsafePointer],
   119  
   120  	// invalid type
   121  	types.Typ[types.Invalid], // only appears in packages with errors
   122  
   123  	// used internally by gc; never used by this package or in .a files
   124  	anyType{},
   125  }
   126  
   127  type anyType struct{}
   128  
   129  func (t anyType) Underlying() types.Type { return t }
   130  func (t anyType) String() string         { return "any" }
   131
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