interp/build: support custom build constraints.

interp/ast.go

@@ -333,7 +333,7 @@ func (interp *Interpreter) ast(src, name string) (string, *node, error) {
 		src = "package main; func main() {" + src + "}"
 	}
 
-	if !interp.buildOk(name, src) {
+	if !interp.buildOk(interp.context, name, src) {
 		return "", nil, nil // skip source not matching build constraints
 	}
 

interp/build.go

@@ -4,14 +4,13 @@ import (
 	"go/build"
 	"go/parser"
 	"path"
-	"runtime"
 	"strconv"
 	"strings"
 )
 
 // buildOk returns true if a file or script matches build constraints
 // as specified in https://golang.org/pkg/go/build/#hdr-Build_Constraints
-func (interp *Interpreter) buildOk(name, src string) bool {
+func (interp *Interpreter) buildOk(ctx build.Context, name, src string) bool {
 	// Extract comments before the first clause
 	f, err := parser.ParseFile(interp.fset, name, src, parser.PackageClauseOnly|parser.ParseComments)
 	if err != nil {
@@ -20,7 +19,7 @@ func (interp *Interpreter) buildOk(name, src string) bool {
 	for _, g := range f.Comments {
 		// in file, evaluate the AND of multiple line build constraints
 		for _, line := range strings.Split(strings.TrimSpace(g.Text()), "\n") {
-			if !buildLineOk(line) {
+			if !buildLineOk(ctx, line) {
 				return false
 			}
 		}
@@ -30,14 +29,14 @@ func (interp *Interpreter) buildOk(name, src string) bool {
 
 // buildLineOk returns true if line is not a build constraint or
 // if build constraint is satisfied
-func buildLineOk(line string) (ok bool) {
+func buildLineOk(ctx build.Context, line string) (ok bool) {
 	if len(line) < 7 || line[:7] != "+build " {
 		return true
 	}
 	// In line, evaluate the OR of space-separated options
 	options := strings.Split(strings.TrimSpace(line[6:]), " ")
 	for _, o := range options {
-		if ok = buildOptionOk(o); ok {
+		if ok = buildOptionOk(ctx, o); ok {
 			break
 		}
 	}
@@ -45,39 +44,35 @@ func buildLineOk(line string) (ok bool) {
 }
 
 // buildOptionOk return true if all comma separated tags match, false otherwise
-func buildOptionOk(tag string) bool {
+func buildOptionOk(ctx build.Context, tag string) bool {
 	// in option, evaluate the AND of individual tags
 	for _, t := range strings.Split(tag, ",") {
-		if !buildTagOk(t) {
+		if !buildTagOk(ctx, t) {
 			return false
 		}
 	}
 	return true
 }
 
-var (
-	goos      = runtime.GOOS
-	goarch    = runtime.GOARCH
-	goversion = goMinorVersion(build.Default)
-)
-
 // buildTagOk returns true if a build tag matches, false otherwise
 // if first character is !, result is negated
-func buildTagOk(s string) (r bool) {
+func buildTagOk(ctx build.Context, s string) (r bool) {
 	not := s[0] == '!'
 	if not {
 		s = s[1:]
 	}
 	switch {
-	case s == goos:
+	case contains(ctx.BuildTags, s):
 		r = true
-	case s == goarch:
+	case s == ctx.GOOS:
+		r = true
+	case s == ctx.GOARCH:
 		r = true
 	case len(s) > 4 && s[:4] == "go1.":
 		if n, err := strconv.Atoi(s[4:]); err != nil {
 			r = false
 		} else {
-			r = goversion >= n
+			r = goMinorVersion(ctx) >= n
 		}
 	}
 	if not {
@@ -86,6 +81,15 @@ func buildTagOk(s string) (r bool) {
 	return
 }
 
+func contains(tags []string, tag string) bool {
+	for _, t := range tags {
+		if t == tag {
+			return true
+		}
+	}
+	return false
+}
+
 // goMinorVersion returns the go minor version number
 func goMinorVersion(ctx build.Context) int {
 	current := ctx.ReleaseTags[len(ctx.ReleaseTags)-1]
@@ -103,7 +107,7 @@ func goMinorVersion(ctx build.Context) int {
 }
 
 // skipFile returns true if file should be skipped
-func skipFile(p string) bool {
+func skipFile(ctx build.Context, p string) bool {
 	if !strings.HasSuffix(p, ".go") {
 		return true
 	}
@@ -117,10 +121,10 @@ func skipFile(p string) bool {
 	}
 	a := strings.Split(p[i+1:], "_")
 	last := len(a) - 1
-	if last1 := last - 1; last1 >= 0 && a[last1] == goos && a[last] == goarch {
+	if last1 := last - 1; last1 >= 0 && a[last1] == ctx.GOOS && a[last] == ctx.GOARCH {
 		return false
 	}
-	if s := a[last]; s != goos && s != goarch && knownOs[s] || knownArch[s] {
+	if s := a[last]; s != ctx.GOOS && s != ctx.GOARCH && knownOs[s] || knownArch[s] {
 		return true
 	}
 	return false

interp/build_test.go

@@ -2,7 +2,6 @@ package interp
 
 import (
 	"go/build"
-	"math"
 	"testing"
 )
 
@@ -13,9 +12,12 @@ type testBuild struct {
 
 func TestBuildTag(t *testing.T) {
 	// Assume a specific OS, arch and go version no matter the real underlying system
-	oo, oa, ov := goos, goarch, goversion
-	goos, goarch, goversion = "linux", "amd64", 11
-	defer func() { goos, goarch, goversion = oo, oa, ov }()
+	ctx := build.Context{
+		GOARCH:      "amd64",
+		GOOS:        "linux",
+		BuildTags:   []string{"foo"},
+		ReleaseTags: []string{"go1.11"},
+	}
 
 	tests := []testBuild{
 		{"// +build linux", true},
@@ -32,6 +34,9 @@ func TestBuildTag(t *testing.T) {
 		{"// +build linux\n// +build amd64", true},
 		{"// +build linux\n\n\n// +build amd64", true},
 		{"// +build linux\n// +build i386", false},
+		{"// +build foo", true},
+		{"// +build !foo", false},
+		{"// +build bar", false},
 	}
 
 	i := New(Options{})
@@ -39,42 +44,7 @@ func TestBuildTag(t *testing.T) {
 		test := test
 		src := test.src + "\npackage x"
 		t.Run(test.src, func(t *testing.T) {
-			if r := i.buildOk("", src); r != test.res {
-				t.Errorf("got %v, want %v", r, test.res)
-			}
-		})
-	}
-}
-
-func TestBuildTagDevel(t *testing.T) {
-	// Assume a specific OS, arch and go version no matter the real underlying system
-	oo, oa, ov := goos, goarch, goversion
-	goos, goarch, goversion = "linux", "amd64", math.MaxInt16
-	defer func() { goos, goarch, goversion = oo, oa, ov }()
-
-	tests := []testBuild{
-		{"// +build linux", true},
-		{"// +build windows", false},
-		{"// +build go1.11", true},
-		{"// +build !go1.12", false},
-		{"// +build go1.12", true},
-		{"// +build !go1.10", false},
-		{"// +build go1.9", true},
-		{"// +build ignore", false},
-		{"// +build linux,amd64", true},
-		{"// +build linux,i386", false},
-		{"// +build linux,i386 go1.11", true},
-		{"// +build linux\n// +build amd64", true},
-		{"// +build linux\n\n\n// +build amd64", true},
-		{"// +build linux\n// +build i386", false},
-	}
-
-	i := New(Options{})
-	for _, test := range tests {
-		test := test
-		src := test.src + "\npackage x"
-		t.Run(test.src, func(t *testing.T) {
-			if r := i.buildOk("", src); r != test.res {
+			if r := i.buildOk(ctx, "", src); r != test.res {
 				t.Errorf("got %v, want %v", r, test.res)
 			}
 		})
@@ -83,9 +53,10 @@ func TestBuildTagDevel(t *testing.T) {
 
 func TestBuildFile(t *testing.T) {
 	// Assume a specific OS, arch and go pattern no matter the real underlying system
-	oo, oa := goos, goarch
-	goos, goarch = "linux", "amd64"
-	defer func() { goos, goarch = oo, oa }()
+	ctx := build.Context{
+		GOARCH: "amd64",
+		GOOS:   "linux",
+	}
 
 	tests := []testBuild{
 		{"foo/bar_linux_amd64.go", false},
@@ -103,7 +74,7 @@ func TestBuildFile(t *testing.T) {
 	for _, test := range tests {
 		test := test
 		t.Run(test.src, func(t *testing.T) {
-			if r := skipFile(test.src); r != test.res {
+			if r := skipFile(ctx, test.src); r != test.res {
 				t.Errorf("got %v, want %v", r, test.res)
 			}
 		})

interp/interp.go

@@ -3,6 +3,7 @@ package interp
 import (
 	"bufio"
 	"fmt"
+	"go/build"
 	"go/scanner"
 	"go/token"
 	"os"
@@ -58,10 +59,10 @@ type Exports map[string]map[string]reflect.Value
 
 // opt stores interpreter options
 type opt struct {
-	astDot bool   // display AST graph (debug)
-	cfgDot bool   // display CFG graph (debug)
-	noRun  bool   // compile, but do not run
-	goPath string // custom GOPATH
+	astDot  bool          // display AST graph (debug)
+	cfgDot  bool          // display CFG graph (debug)
+	noRun   bool          // compile, but do not run
+	context build.Context // build context: GOPATH, build constraints
 }
 
 // Interpreter contains global resources and state
@@ -118,12 +119,14 @@ func (n *node) Walk(in func(n *node) bool, out func(n *node)) {
 type Options struct {
 	// GoPath sets GOPATH for the interpreter
 	GoPath string
+	// BuildTags sets build constraints for the interpreter
+	BuildTags []string
 }
 
 // New returns a new interpreter
 func New(options Options) *Interpreter {
 	i := Interpreter{
-		opt:      opt{goPath: options.GoPath},
+		opt:      opt{context: build.Default},
 		fset:     token.NewFileSet(),
 		universe: initUniverse(),
 		scopes:   map[string]*scope{},
@@ -131,6 +134,11 @@ func New(options Options) *Interpreter {
 		frame:    &frame{data: []reflect.Value{}},
 	}
 
+	i.opt.context.GOPATH = options.GoPath
+	if len(options.BuildTags) > 0 {
+		i.opt.context.BuildTags = options.BuildTags
+	}
+
 	// AstDot activates AST graph display for the interpreter
 	i.opt.astDot, _ = strconv.ParseBool(os.Getenv("YAEGI_AST_DOT"))
 

interp/src.go

@@ -22,7 +22,7 @@ func (interp *Interpreter) importSrcFile(rPath, path, alias string) error {
 			rPath = "."
 		}
 		dir = filepath.Join(filepath.Dir(interp.Name), rPath, path)
-	} else if dir, rPath, err = pkgDir(interp.goPath, rPath, path); err != nil {
+	} else if dir, rPath, err = pkgDir(interp.context.GOPATH, rPath, path); err != nil {
 		return err
 	}
 
@@ -40,7 +40,7 @@ func (interp *Interpreter) importSrcFile(rPath, path, alias string) error {
 	// Parse source files
 	for _, file := range files {
 		name := file.Name()
-		if skipFile(name) {
+		if skipFile(interp.context, name) {
 			continue
 		}