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package source // import "gotest.tools/internal/source"
import (
"bytes"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"os"
"runtime"
"strconv"
"strings"
"github.com/pkg/errors"
)
const baseStackIndex = 1
// FormattedCallExprArg returns the argument from an ast.CallExpr at the
// index in the call stack. The argument is formatted using FormatNode.
func FormattedCallExprArg(stackIndex int, argPos int) (string, error) {
args, err := CallExprArgs(stackIndex + 1)
if err != nil {
return "", err
}
return FormatNode(args[argPos])
}
func getNodeAtLine(filename string, lineNum int) (ast.Node, error) {
fileset := token.NewFileSet()
astFile, err := parser.ParseFile(fileset, filename, nil, parser.AllErrors)
if err != nil {
return nil, errors.Wrapf(err, "failed to parse source file: %s", filename)
}
node := scanToLine(fileset, astFile, lineNum)
if node == nil {
return nil, errors.Errorf(
"failed to find an expression on line %d in %s", lineNum, filename)
}
return node, nil
}
func scanToLine(fileset *token.FileSet, node ast.Node, lineNum int) ast.Node {
v := &scanToLineVisitor{lineNum: lineNum, fileset: fileset}
ast.Walk(v, node)
return v.matchedNode
}
type scanToLineVisitor struct {
lineNum int
matchedNode ast.Node
fileset *token.FileSet
}
func (v *scanToLineVisitor) Visit(node ast.Node) ast.Visitor {
if node == nil || v.matchedNode != nil {
return nil
}
if v.nodePosition(node).Line == v.lineNum {
v.matchedNode = node
return nil
}
return v
}
// In golang 1.9 the line number changed from being the line where the statement
// ended to the line where the statement began.
func (v *scanToLineVisitor) nodePosition(node ast.Node) token.Position {
if goVersionBefore19 {
return v.fileset.Position(node.End())
}
return v.fileset.Position(node.Pos())
}
var goVersionBefore19 = isGOVersionBefore19()
func isGOVersionBefore19() bool {
version := runtime.Version()
// not a release version
if !strings.HasPrefix(version, "go") {
return false
}
version = strings.TrimPrefix(version, "go")
parts := strings.Split(version, ".")
if len(parts) < 2 {
return false
}
minor, err := strconv.ParseInt(parts[1], 10, 32)
return err == nil && parts[0] == "1" && minor < 9
}
func getCallExprArgs(node ast.Node) ([]ast.Expr, error) {
visitor := &callExprVisitor{}
ast.Walk(visitor, node)
if visitor.expr == nil {
return nil, errors.New("failed to find call expression")
}
return visitor.expr.Args, nil
}
type callExprVisitor struct {
expr *ast.CallExpr
}
func (v *callExprVisitor) Visit(node ast.Node) ast.Visitor {
if v.expr != nil || node == nil {
return nil
}
debug("visit (%T): %s", node, debugFormatNode{node})
if callExpr, ok := node.(*ast.CallExpr); ok {
v.expr = callExpr
return nil
}
return v
}
// FormatNode using go/format.Node and return the result as a string
func FormatNode(node ast.Node) (string, error) {
buf := new(bytes.Buffer)
err := format.Node(buf, token.NewFileSet(), node)
return buf.String(), err
}
// CallExprArgs returns the ast.Expr slice for the args of an ast.CallExpr at
// the index in the call stack.
func CallExprArgs(stackIndex int) ([]ast.Expr, error) {
_, filename, lineNum, ok := runtime.Caller(baseStackIndex + stackIndex)
if !ok {
return nil, errors.New("failed to get call stack")
}
debug("call stack position: %s:%d", filename, lineNum)
node, err := getNodeAtLine(filename, lineNum)
if err != nil {
return nil, err
}
debug("found node (%T): %s", node, debugFormatNode{node})
return getCallExprArgs(node)
}
var debugEnabled = os.Getenv("GOTESTYOURSELF_DEBUG") != ""
func debug(format string, args ...interface{}) {
if debugEnabled {
fmt.Fprintf(os.Stderr, "DEBUG: "+format+"\n", args...)
}
}
type debugFormatNode struct {
ast.Node
}
func (n debugFormatNode) String() string {
out, err := FormatNode(n.Node)
if err != nil {
return fmt.Sprintf("failed to format %s: %s", n.Node, err)
}
return out
}
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