1 files changed, 94 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/syntax/syntax.go b/src/cmd/compile/internal/syntax/syntax.go
new file mode 100644
index 0000000..83b102d
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/syntax.go
@@ -0,0 +1,94 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syntax
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// Mode describes the parser mode.
+type Mode uint
+
+// Modes supported by the parser.
+const (
+	CheckBranches Mode = 1 << iota // check correct use of labels, break, continue, and goto statements
+)
+
+// Error describes a syntax error. Error implements the error interface.
+type Error struct {
+	Pos Pos
+	Msg string
+}
+
+func (err Error) Error() string {
+	return fmt.Sprintf("%s: %s", err.Pos, err.Msg)
+}
+
+var _ error = Error{} // verify that Error implements error
+
+// An ErrorHandler is called for each error encountered reading a .go file.
+type ErrorHandler func(err error)
+
+// A Pragma value augments a package, import, const, func, type, or var declaration.
+// Its meaning is entirely up to the PragmaHandler,
+// except that nil is used to mean “no pragma seen.”
+type Pragma interface{}
+
+// A PragmaHandler is used to process //go: directives while scanning.
+// It is passed the current pragma value, which starts out being nil,
+// and it returns an updated pragma value.
+// The text is the directive, with the "//" prefix stripped.
+// The current pragma is saved at each package, import, const, func, type, or var
+// declaration, into the File, ImportDecl, ConstDecl, FuncDecl, TypeDecl, or VarDecl node.
+//
+// If text is the empty string, the pragma is being returned
+// to the handler unused, meaning it appeared before a non-declaration.
+// The handler may wish to report an error. In this case, pos is the
+// current parser position, not the position of the pragma itself.
+// Blank specifies whether the line is blank before the pragma.
+type PragmaHandler func(pos Pos, blank bool, text string, current Pragma) Pragma
+
+// Parse parses a single Go source file from src and returns the corresponding
+// syntax tree. If there are errors, Parse will return the first error found,
+// and a possibly partially constructed syntax tree, or nil.
+//
+// If errh != nil, it is called with each error encountered, and Parse will
+// process as much source as possible. In this case, the returned syntax tree
+// is only nil if no correct package clause was found.
+// If errh is nil, Parse will terminate immediately upon encountering the first
+// error, and the returned syntax tree is nil.
+//
+// If pragh != nil, it is called with each pragma encountered.
+func Parse(base *PosBase, src io.Reader, errh ErrorHandler, pragh PragmaHandler, mode Mode) (_ *File, first error) {
+	defer func() {
+		if p := recover(); p != nil {
+			if err, ok := p.(Error); ok {
+				first = err
+				return
+			}
+			panic(p)
+		}
+	}()
+
+	var p parser
+	p.init(base, src, errh, pragh, mode)
+	p.next()
+	return p.fileOrNil(), p.first
+}
+
+// ParseFile behaves like Parse but it reads the source from the named file.
+func ParseFile(filename string, errh ErrorHandler, pragh PragmaHandler, mode Mode) (*File, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		if errh != nil {
+			errh(err)
+		}
+		return nil, err
+	}
+	defer f.Close()
+	return Parse(NewFileBase(filename), f, errh, pragh, mode)
+}