Implement git refs API for listing references (branches, tags and other) (#5354)

* Inital routes to git refs api

* Git refs API implementation

* Update swagger

* Fix copyright

* Make swagger happy add basic test

* Fix test

* Fix test again :)

17 files changed, 2052 insertions, 0 deletions

diff --git a/vendor/github.com/src-d/gcfg/LICENSE b/vendor/github.com/src-d/gcfg/LICENSE
new file mode 100644
index 0000000000..87a5cede33
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/LICENSE
@@ -0,0 +1,28 @@
+Copyright (c) 2012 Péter Surányi. Portions Copyright (c) 2009 The Go
+Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/src-d/gcfg/doc.go b/vendor/github.com/src-d/gcfg/doc.go
new file mode 100644
index 0000000000..2edcb41a08
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/doc.go
@@ -0,0 +1,145 @@
+// Package gcfg reads "INI-style" text-based configuration files with
+// "name=value" pairs grouped into sections (gcfg files).
+//
+// This package is still a work in progress; see the sections below for planned
+// changes.
+//
+// Syntax
+//
+// The syntax is based on that used by git config:
+// http://git-scm.com/docs/git-config#_syntax .
+// There are some (planned) differences compared to the git config format:
+//  - improve data portability:
+//    - must be encoded in UTF-8 (for now) and must not contain the 0 byte
+//    - include and "path" type is not supported
+//      (path type may be implementable as a user-defined type)
+//  - internationalization
+//    - section and variable names can contain unicode letters, unicode digits
+//      (as defined in http://golang.org/ref/spec#Characters ) and hyphens
+//      (U+002D), starting with a unicode letter
+//  - disallow potentially ambiguous or misleading definitions:
+//    - `[sec.sub]` format is not allowed (deprecated in gitconfig)
+//    - `[sec ""]` is not allowed
+//      - use `[sec]` for section name "sec" and empty subsection name
+//    - (planned) within a single file, definitions must be contiguous for each:
+//      - section: '[secA]' -> '[secB]' -> '[secA]' is an error
+//      - subsection: '[sec "A"]' -> '[sec "B"]' -> '[sec "A"]' is an error
+//      - multivalued variable: 'multi=a' -> 'other=x' -> 'multi=b' is an error
+//
+// Data structure
+//
+// The functions in this package read values into a user-defined struct.
+// Each section corresponds to a struct field in the config struct, and each
+// variable in a section corresponds to a data field in the section struct.
+// The mapping of each section or variable name to fields is done either based
+// on the "gcfg" struct tag or by matching the name of the section or variable,
+// ignoring case. In the latter case, hyphens '-' in section and variable names
+// correspond to underscores '_' in field names.
+// Fields must be exported; to use a section or variable name starting with a
+// letter that is neither upper- or lower-case, prefix the field name with 'X'.
+// (See https://code.google.com/p/go/issues/detail?id=5763#c4 .)
+//
+// For sections with subsections, the corresponding field in config must be a
+// map, rather than a struct, with string keys and pointer-to-struct values.
+// Values for subsection variables are stored in the map with the subsection
+// name used as the map key.
+// (Note that unlike section and variable names, subsection names are case
+// sensitive.)
+// When using a map, and there is a section with the same section name but
+// without a subsection name, its values are stored with the empty string used
+// as the key.
+// It is possible to provide default values for subsections in the section
+// "default-<sectionname>" (or by setting values in the corresponding struct
+// field "Default_<sectionname>").
+//
+// The functions in this package panic if config is not a pointer to a struct,
+// or when a field is not of a suitable type (either a struct or a map with
+// string keys and pointer-to-struct values).
+//
+// Parsing of values
+//
+// The section structs in the config struct may contain single-valued or
+// multi-valued variables. Variables of unnamed slice type (that is, a type
+// starting with `[]`) are treated as multi-value; all others (including named
+// slice types) are treated as single-valued variables.
+//
+// Single-valued variables are handled based on the type as follows.
+// Unnamed pointer types (that is, types starting with `*`) are dereferenced,
+// and if necessary, a new instance is allocated.
+//
+// For types implementing the encoding.TextUnmarshaler interface, the
+// UnmarshalText method is used to set the value. Implementing this method is
+// the recommended way for parsing user-defined types.
+//
+// For fields of string kind, the value string is assigned to the field, after
+// unquoting and unescaping as needed.
+// For fields of bool kind, the field is set to true if the value is "true",
+// "yes", "on" or "1", and set to false if the value is "false", "no", "off" or
+// "0", ignoring case. In addition, single-valued bool fields can be specified
+// with a "blank" value (variable name without equals sign and value); in such
+// case the value is set to true.
+//
+// Predefined integer types [u]int(|8|16|32|64) and big.Int are parsed as
+// decimal or hexadecimal (if having '0x' prefix). (This is to prevent
+// unintuitively handling zero-padded numbers as octal.) Other types having
+// [u]int* as the underlying type, such as os.FileMode and uintptr allow
+// decimal, hexadecimal, or octal values.
+// Parsing mode for integer types can be overridden using the struct tag option
+// ",int=mode" where mode is a combination of the 'd', 'h', and 'o' characters
+// (each standing for decimal, hexadecimal, and octal, respectively.)
+//
+// All other types are parsed using fmt.Sscanf with the "%v" verb.
+//
+// For multi-valued variables, each individual value is parsed as above and
+// appended to the slice. If the first value is specified as a "blank" value
+// (variable name without equals sign and value), a new slice is allocated;
+// that is any values previously set in the slice will be ignored.
+//
+// The types subpackage for provides helpers for parsing "enum-like" and integer
+// types.
+//
+// Error handling
+//
+// There are 3 types of errors:
+//
+//  - programmer errors / panics:
+//    - invalid configuration structure
+//  - data errors:
+//    - fatal errors:
+//      - invalid configuration syntax
+//    - warnings:
+//      - data that doesn't belong to any part of the config structure
+//
+// Programmer errors trigger panics. These are should be fixed by the programmer
+// before releasing code that uses gcfg.
+//
+// Data errors cause gcfg to return a non-nil error value. This includes the
+// case when there are extra unknown key-value definitions in the configuration
+// data (extra data).
+// However, in some occasions it is desirable to be able to proceed in
+// situations when the only data error is that of extra data.
+// These errors are handled at a different (warning) priority and can be
+// filtered out programmatically. To ignore extra data warnings, wrap the
+// gcfg.Read*Into invocation into a call to gcfg.FatalOnly.
+//
+// TODO
+//
+// The following is a list of changes under consideration:
+//  - documentation
+//    - self-contained syntax documentation
+//    - more practical examples
+//    - move TODOs to issue tracker (eventually)
+//  - syntax
+//    - reconsider valid escape sequences
+//      (gitconfig doesn't support \r in value, \t in subsection name, etc.)
+//  - reading / parsing gcfg files
+//    - define internal representation structure
+//    - support multiple inputs (readers, strings, files)
+//    - support declaring encoding (?)
+//    - support varying fields sets for subsections (?)
+//  - writing gcfg files
+//  - error handling
+//    - make error context accessible programmatically?
+//    - limit input size?
+//
+package gcfg // import "github.com/src-d/gcfg"
diff --git a/vendor/github.com/src-d/gcfg/errors.go b/vendor/github.com/src-d/gcfg/errors.go
new file mode 100644
index 0000000000..853c76021d
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/errors.go
@@ -0,0 +1,41 @@
+package gcfg
+
+import (
+	"gopkg.in/warnings.v0"
+)
+
+// FatalOnly filters the results of a Read*Into invocation and returns only
+// fatal errors. That is, errors (warnings) indicating data for unknown
+// sections / variables is ignored. Example invocation:
+//
+//  err := gcfg.FatalOnly(gcfg.ReadFileInto(&cfg, configFile))
+//  if err != nil {
+//      ...
+//
+func FatalOnly(err error) error {
+	return warnings.FatalOnly(err)
+}
+
+func isFatal(err error) bool {
+	_, ok := err.(extraData)
+	return !ok
+}
+
+type extraData struct {
+	section    string
+	subsection *string
+	variable   *string
+}
+
+func (e extraData) Error() string {
+	s := "can't store data at section \"" + e.section + "\""
+	if e.subsection != nil {
+		s += ", subsection \"" + *e.subsection + "\""
+	}
+	if e.variable != nil {
+		s += ", variable \"" + *e.variable + "\""
+	}
+	return s
+}
+
+var _ error = extraData{}
diff --git a/vendor/github.com/src-d/gcfg/go1_0.go b/vendor/github.com/src-d/gcfg/go1_0.go
new file mode 100644
index 0000000000..6670210791
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/go1_0.go
@@ -0,0 +1,7 @@
+// +build !go1.2
+
+package gcfg
+
+type textUnmarshaler interface {
+	UnmarshalText(text []byte) error
+}
diff --git a/vendor/github.com/src-d/gcfg/go1_2.go b/vendor/github.com/src-d/gcfg/go1_2.go
new file mode 100644
index 0000000000..6f5843bc7c
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/go1_2.go
@@ -0,0 +1,9 @@
+// +build go1.2
+
+package gcfg
+
+import (
+	"encoding"
+)
+
+type textUnmarshaler encoding.TextUnmarshaler
diff --git a/vendor/github.com/src-d/gcfg/read.go b/vendor/github.com/src-d/gcfg/read.go
new file mode 100644
index 0000000000..fff0448c78
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/read.go
@@ -0,0 +1,273 @@
+package gcfg
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"github.com/src-d/gcfg/scanner"
+	"github.com/src-d/gcfg/token"
+	"gopkg.in/warnings.v0"
+)
+
+var unescape = map[rune]rune{'\\': '\\', '"': '"', 'n': '\n', 't': '\t', 'b': '\b'}
+
+// no error: invalid literals should be caught by scanner
+func unquote(s string) string {
+	u, q, esc := make([]rune, 0, len(s)), false, false
+	for _, c := range s {
+		if esc {
+			uc, ok := unescape[c]
+			switch {
+			case ok:
+				u = append(u, uc)
+				fallthrough
+			case !q && c == '\n':
+				esc = false
+				continue
+			}
+			panic("invalid escape sequence")
+		}
+		switch c {
+		case '"':
+			q = !q
+		case '\\':
+			esc = true
+		default:
+			u = append(u, c)
+		}
+	}
+	if q {
+		panic("missing end quote")
+	}
+	if esc {
+		panic("invalid escape sequence")
+	}
+	return string(u)
+}
+
+func read(c *warnings.Collector, callback func(string, string, string, string, bool) error,
+	fset *token.FileSet, file *token.File, src []byte) error {
+	//
+	var s scanner.Scanner
+	var errs scanner.ErrorList
+	s.Init(file, src, func(p token.Position, m string) { errs.Add(p, m) }, 0)
+	sect, sectsub := "", ""
+	pos, tok, lit := s.Scan()
+	errfn := func(msg string) error {
+		return fmt.Errorf("%s: %s", fset.Position(pos), msg)
+	}
+	for {
+		if errs.Len() > 0 {
+			if err := c.Collect(errs.Err()); err != nil {
+				return err
+			}
+		}
+		switch tok {
+		case token.EOF:
+			return nil
+		case token.EOL, token.COMMENT:
+			pos, tok, lit = s.Scan()
+		case token.LBRACK:
+			pos, tok, lit = s.Scan()
+			if errs.Len() > 0 {
+				if err := c.Collect(errs.Err()); err != nil {
+					return err
+				}
+			}
+			if tok != token.IDENT {
+				if err := c.Collect(errfn("expected section name")); err != nil {
+					return err
+				}
+			}
+			sect, sectsub = lit, ""
+			pos, tok, lit = s.Scan()
+			if errs.Len() > 0 {
+				if err := c.Collect(errs.Err()); err != nil {
+					return err
+				}
+			}
+			if tok == token.STRING {
+				sectsub = unquote(lit)
+				if sectsub == "" {
+					if err := c.Collect(errfn("empty subsection name")); err != nil {
+						return err
+					}
+				}
+				pos, tok, lit = s.Scan()
+				if errs.Len() > 0 {
+					if err := c.Collect(errs.Err()); err != nil {
+						return err
+					}
+				}
+			}
+			if tok != token.RBRACK {
+				if sectsub == "" {
+					if err := c.Collect(errfn("expected subsection name or right bracket")); err != nil {
+						return err
+					}
+				}
+				if err := c.Collect(errfn("expected right bracket")); err != nil {
+					return err
+				}
+			}
+			pos, tok, lit = s.Scan()
+			if tok != token.EOL && tok != token.EOF && tok != token.COMMENT {
+				if err := c.Collect(errfn("expected EOL, EOF, or comment")); err != nil {
+					return err
+				}
+			}
+			// If a section/subsection header was found, ensure a
+			// container object is created, even if there are no
+			// variables further down.
+			err := c.Collect(callback(sect, sectsub, "", "", true))
+			if err != nil {
+				return err
+			}
+		case token.IDENT:
+			if sect == "" {
+				if err := c.Collect(errfn("expected section header")); err != nil {
+					return err
+				}
+			}
+			n := lit
+			pos, tok, lit = s.Scan()
+			if errs.Len() > 0 {
+				return errs.Err()
+			}
+			blank, v := tok == token.EOF || tok == token.EOL || tok == token.COMMENT, ""
+			if !blank {
+				if tok != token.ASSIGN {
+					if err := c.Collect(errfn("expected '='")); err != nil {
+						return err
+					}
+				}
+				pos, tok, lit = s.Scan()
+				if errs.Len() > 0 {
+					if err := c.Collect(errs.Err()); err != nil {
+						return err
+					}
+				}
+				if tok != token.STRING {
+					if err := c.Collect(errfn("expected value")); err != nil {
+						return err
+					}
+				}
+				v = unquote(lit)
+				pos, tok, lit = s.Scan()
+				if errs.Len() > 0 {
+					if err := c.Collect(errs.Err()); err != nil {
+						return err
+					}
+				}
+				if tok != token.EOL && tok != token.EOF && tok != token.COMMENT {
+					if err := c.Collect(errfn("expected EOL, EOF, or comment")); err != nil {
+						return err
+					}
+				}
+			}
+			err := c.Collect(callback(sect, sectsub, n, v, blank))
+			if err != nil {
+				return err
+			}
+		default:
+			if sect == "" {
+				if err := c.Collect(errfn("expected section header")); err != nil {
+					return err
+				}
+			}
+			if err := c.Collect(errfn("expected section header or variable declaration")); err != nil {
+				return err
+			}
+		}
+	}
+	panic("never reached")
+}
+
+func readInto(config interface{}, fset *token.FileSet, file *token.File,
+	src []byte) error {
+	//
+	c := warnings.NewCollector(isFatal)
+	firstPassCallback := func(s string, ss string, k string, v string, bv bool) error {
+		return set(c, config, s, ss, k, v, bv, false)
+	}
+	err := read(c, firstPassCallback, fset, file, src)
+	if err != nil {
+		return err
+	}
+	secondPassCallback := func(s string, ss string, k string, v string, bv bool) error {
+		return set(c, config, s, ss, k, v, bv, true)
+	}
+	err = read(c, secondPassCallback, fset, file, src)
+	if err != nil {
+		return err
+	}
+	return c.Done()
+}
+
+// ReadWithCallback reads gcfg formatted data from reader and calls
+// callback with each section and option found.
+//
+// Callback is called with section, subsection, option key, option value
+// and blank value flag as arguments.
+//
+// When a section is found, callback is called with nil subsection, option key
+// and option value.
+//
+// When a subsection is found, callback is called with nil option key and
+// option value.
+//
+// If blank value flag is true, it means that the value was not set for an option
+// (as opposed to set to empty string).
+//
+// If callback returns an error, ReadWithCallback terminates with an error too.
+func ReadWithCallback(reader io.Reader, callback func(string, string, string, string, bool) error) error {
+	src, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return err
+	}
+
+	fset := token.NewFileSet()
+	file := fset.AddFile("", fset.Base(), len(src))
+	c := warnings.NewCollector(isFatal)
+
+	return read(c, callback, fset, file, src)
+}
+
+// ReadInto reads gcfg formatted data from reader and sets the values into the
+// corresponding fields in config.
+func ReadInto(config interface{}, reader io.Reader) error {
+	src, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return err
+	}
+	fset := token.NewFileSet()
+	file := fset.AddFile("", fset.Base(), len(src))
+	return readInto(config, fset, file, src)
+}
+
+// ReadStringInto reads gcfg formatted data from str and sets the values into
+// the corresponding fields in config.
+func ReadStringInto(config interface{}, str string) error {
+	r := strings.NewReader(str)
+	return ReadInto(config, r)
+}
+
+// ReadFileInto reads gcfg formatted data from the file filename and sets the
+// values into the corresponding fields in config.
+func ReadFileInto(config interface{}, filename string) error {
+	f, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	src, err := ioutil.ReadAll(f)
+	if err != nil {
+		return err
+	}
+	fset := token.NewFileSet()
+	file := fset.AddFile(filename, fset.Base(), len(src))
+	return readInto(config, fset, file, src)
+}
diff --git a/vendor/github.com/src-d/gcfg/scanner/errors.go b/vendor/github.com/src-d/gcfg/scanner/errors.go
new file mode 100644
index 0000000000..f3fcecacbb
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/scanner/errors.go
@@ -0,0 +1,121 @@
+// Copyright 2009 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 scanner
+
+import (
+	"fmt"
+	"io"
+	"sort"
+)
+
+import (
+	"github.com/src-d/gcfg/token"
+)
+
+// In an ErrorList, an error is represented by an *Error.
+// The position Pos, if valid, points to the beginning of
+// the offending token, and the error condition is described
+// by Msg.
+//
+type Error struct {
+	Pos token.Position
+	Msg string
+}
+
+// Error implements the error interface.
+func (e Error) Error() string {
+	if e.Pos.Filename != "" || e.Pos.IsValid() {
+		// don't print "<unknown position>"
+		// TODO(gri) reconsider the semantics of Position.IsValid
+		return e.Pos.String() + ": " + e.Msg
+	}
+	return e.Msg
+}
+
+// ErrorList is a list of *Errors.
+// The zero value for an ErrorList is an empty ErrorList ready to use.
+//
+type ErrorList []*Error
+
+// Add adds an Error with given position and error message to an ErrorList.
+func (p *ErrorList) Add(pos token.Position, msg string) {
+	*p = append(*p, &Error{pos, msg})
+}
+
+// Reset resets an ErrorList to no errors.
+func (p *ErrorList) Reset() { *p = (*p)[0:0] }
+
+// ErrorList implements the sort Interface.
+func (p ErrorList) Len() int      { return len(p) }
+func (p ErrorList) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
+
+func (p ErrorList) Less(i, j int) bool {
+	e := &p[i].Pos
+	f := &p[j].Pos
+	if e.Filename < f.Filename {
+		return true
+	}
+	if e.Filename == f.Filename {
+		return e.Offset < f.Offset
+	}
+	return false
+}
+
+// Sort sorts an ErrorList. *Error entries are sorted by position,
+// other errors are sorted by error message, and before any *Error
+// entry.
+//
+func (p ErrorList) Sort() {
+	sort.Sort(p)
+}
+
+// RemoveMultiples sorts an ErrorList and removes all but the first error per line.
+func (p *ErrorList) RemoveMultiples() {
+	sort.Sort(p)
+	var last token.Position // initial last.Line is != any legal error line
+	i := 0
+	for _, e := range *p {
+		if e.Pos.Filename != last.Filename || e.Pos.Line != last.Line {
+			last = e.Pos
+			(*p)[i] = e
+			i++
+		}
+	}
+	(*p) = (*p)[0:i]
+}
+
+// An ErrorList implements the error interface.
+func (p ErrorList) Error() string {
+	switch len(p) {
+	case 0:
+		return "no errors"
+	case 1:
+		return p[0].Error()
+	}
+	return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
+}
+
+// Err returns an error equivalent to this error list.
+// If the list is empty, Err returns nil.
+func (p ErrorList) Err() error {
+	if len(p) == 0 {
+		return nil
+	}
+	return p
+}
+
+// PrintError is a utility function that prints a list of errors to w,
+// one error per line, if the err parameter is an ErrorList. Otherwise
+// it prints the err string.
+//
+func PrintError(w io.Writer, err error) {
+	if list, ok := err.(ErrorList); ok {
+		for _, e := range list {
+			fmt.Fprintf(w, "%s\n", e)
+		}
+	} else if err != nil {
+		fmt.Fprintf(w, "%s\n", err)
+	}
+}
diff --git a/vendor/github.com/src-d/gcfg/scanner/scanner.go b/vendor/github.com/src-d/gcfg/scanner/scanner.go
new file mode 100644
index 0000000000..b1eef06f69
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/scanner/scanner.go
@@ -0,0 +1,342 @@
+// Copyright 2009 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 scanner implements a scanner for gcfg configuration text.
+// It takes a []byte as source which can then be tokenized
+// through repeated calls to the Scan method.
+//
+// Note that the API for the scanner package may change to accommodate new
+// features or implementation changes in gcfg.
+//
+package scanner
+
+import (
+	"fmt"
+	"path/filepath"
+	"unicode"
+	"unicode/utf8"
+)
+
+import (
+	"github.com/src-d/gcfg/token"
+)
+
+// An ErrorHandler may be provided to Scanner.Init. If a syntax error is
+// encountered and a handler was installed, the handler is called with a
+// position and an error message. The position points to the beginning of
+// the offending token.
+//
+type ErrorHandler func(pos token.Position, msg string)
+
+// A Scanner holds the scanner's internal state while processing
+// a given text.  It can be allocated as part of another data
+// structure but must be initialized via Init before use.
+//
+type Scanner struct {
+	// immutable state
+	file *token.File  // source file handle
+	dir  string       // directory portion of file.Name()
+	src  []byte       // source
+	err  ErrorHandler // error reporting; or nil
+	mode Mode         // scanning mode
+
+	// scanning state
+	ch         rune // current character
+	offset     int  // character offset
+	rdOffset   int  // reading offset (position after current character)
+	lineOffset int  // current line offset
+	nextVal    bool // next token is expected to be a value
+
+	// public state - ok to modify
+	ErrorCount int // number of errors encountered
+}
+
+// Read the next Unicode char into s.ch.
+// s.ch < 0 means end-of-file.
+//
+func (s *Scanner) next() {
+	if s.rdOffset < len(s.src) {
+		s.offset = s.rdOffset
+		if s.ch == '\n' {
+			s.lineOffset = s.offset
+			s.file.AddLine(s.offset)
+		}
+		r, w := rune(s.src[s.rdOffset]), 1
+		switch {
+		case r == 0:
+			s.error(s.offset, "illegal character NUL")
+		case r >= 0x80:
+			// not ASCII
+			r, w = utf8.DecodeRune(s.src[s.rdOffset:])
+			if r == utf8.RuneError && w == 1 {
+				s.error(s.offset, "illegal UTF-8 encoding")
+			}
+		}
+		s.rdOffset += w
+		s.ch = r
+	} else {
+		s.offset = len(s.src)
+		if s.ch == '\n' {
+			s.lineOffset = s.offset
+			s.file.AddLine(s.offset)
+		}
+		s.ch = -1 // eof
+	}
+}
+
+// A mode value is a set of flags (or 0).
+// They control scanner behavior.
+//
+type Mode uint
+
+const (
+	ScanComments Mode = 1 << iota // return comments as COMMENT tokens
+)
+
+// Init prepares the scanner s to tokenize the text src by setting the
+// scanner at the beginning of src. The scanner uses the file set file
+// for position information and it adds line information for each line.
+// It is ok to re-use the same file when re-scanning the same file as
+// line information which is already present is ignored. Init causes a
+// panic if the file size does not match the src size.
+//
+// Calls to Scan will invoke the error handler err if they encounter a
+// syntax error and err is not nil. Also, for each error encountered,
+// the Scanner field ErrorCount is incremented by one. The mode parameter
+// determines how comments are handled.
+//
+// Note that Init may call err if there is an error in the first character
+// of the file.
+//
+func (s *Scanner) Init(file *token.File, src []byte, err ErrorHandler, mode Mode) {
+	// Explicitly initialize all fields since a scanner may be reused.
+	if file.Size() != len(src) {
+		panic(fmt.Sprintf("file size (%d) does not match src len (%d)", file.Size(), len(src)))
+	}
+	s.file = file
+	s.dir, _ = filepath.Split(file.Name())
+	s.src = src
+	s.err = err
+	s.mode = mode
+
+	s.ch = ' '
+	s.offset = 0
+	s.rdOffset = 0
+	s.lineOffset = 0
+	s.ErrorCount = 0
+	s.nextVal = false
+
+	s.next()
+}
+
+func (s *Scanner) error(offs int, msg string) {
+	if s.err != nil {
+		s.err(s.file.Position(s.file.Pos(offs)), msg)
+	}
+	s.ErrorCount++
+}
+
+func (s *Scanner) scanComment() string {
+	// initial [;#] already consumed
+	offs := s.offset - 1 // position of initial [;#]
+
+	for s.ch != '\n' && s.ch >= 0 {
+		s.next()
+	}
+	return string(s.src[offs:s.offset])
+}
+
+func isLetter(ch rune) bool {
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch >= 0x80 && unicode.IsLetter(ch)
+}
+
+func isDigit(ch rune) bool {
+	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
+}
+
+func (s *Scanner) scanIdentifier() string {
+	offs := s.offset
+	for isLetter(s.ch) || isDigit(s.ch) || s.ch == '-' {
+		s.next()
+	}
+	return string(s.src[offs:s.offset])
+}
+
+func (s *Scanner) scanEscape(val bool) {
+	offs := s.offset
+	ch := s.ch
+	s.next() // always make progress
+	switch ch {
+	case '\\', '"':
+		// ok
+	case 'n', 't', 'b':
+		if val {
+			break // ok
+		}
+		fallthrough
+	default:
+		s.error(offs, "unknown escape sequence")
+	}
+}
+
+func (s *Scanner) scanString() string {
+	// '"' opening already consumed
+	offs := s.offset - 1
+
+	for s.ch != '"' {
+		ch := s.ch
+		s.next()
+		if ch == '\n' || ch < 0 {
+			s.error(offs, "string not terminated")
+			break
+		}
+		if ch == '\\' {
+			s.scanEscape(false)
+		}
+	}
+
+	s.next()
+
+	return string(s.src[offs:s.offset])
+}
+
+func stripCR(b []byte) []byte {
+	c := make([]byte, len(b))
+	i := 0
+	for _, ch := range b {
+		if ch != '\r' {
+			c[i] = ch
+			i++
+		}
+	}
+	return c[:i]
+}
+
+func (s *Scanner) scanValString() string {
+	offs := s.offset
+
+	hasCR := false
+	end := offs
+	inQuote := false
+loop:
+	for inQuote || s.ch >= 0 && s.ch != '\n' && s.ch != ';' && s.ch != '#' {
+		ch := s.ch
+		s.next()
+		switch {
+		case inQuote && ch == '\\':
+			s.scanEscape(true)
+		case !inQuote && ch == '\\':
+			if s.ch == '\r' {
+				hasCR = true
+				s.next()
+			}
+			if s.ch != '\n' {
+				s.scanEscape(true)
+			} else {
+				s.next()
+			}
+		case ch == '"':
+			inQuote = !inQuote
+		case ch == '\r':
+			hasCR = true
+		case ch < 0 || inQuote && ch == '\n':
+			s.error(offs, "string not terminated")
+			break loop
+		}
+		if inQuote || !isWhiteSpace(ch) {
+			end = s.offset
+		}
+	}
+
+	lit := s.src[offs:end]
+	if hasCR {
+		lit = stripCR(lit)
+	}
+
+	return string(lit)
+}
+
+func isWhiteSpace(ch rune) bool {
+	return ch == ' ' || ch == '\t' || ch == '\r'
+}
+
+func (s *Scanner) skipWhitespace() {
+	for isWhiteSpace(s.ch) {
+		s.next()
+	}
+}
+
+// Scan scans the next token and returns the token position, the token,
+// and its literal string if applicable. The source end is indicated by
+// token.EOF.
+//
+// If the returned token is a literal (token.IDENT, token.STRING) or
+// token.COMMENT, the literal string has the corresponding value.
+//
+// If the returned token is token.ILLEGAL, the literal string is the
+// offending character.
+//
+// In all other cases, Scan returns an empty literal string.
+//
+// For more tolerant parsing, Scan will return a valid token if
+// possible even if a syntax error was encountered. Thus, even
+// if the resulting token sequence contains no illegal tokens,
+// a client may not assume that no error occurred. Instead it
+// must check the scanner's ErrorCount or the number of calls
+// of the error handler, if there was one installed.
+//
+// Scan adds line information to the file added to the file
+// set with Init. Token positions are relative to that file
+// and thus relative to the file set.
+//
+func (s *Scanner) Scan() (pos token.Pos, tok token.Token, lit string) {
+scanAgain:
+	s.skipWhitespace()
+
+	// current token start
+	pos = s.file.Pos(s.offset)
+
+	// determine token value
+	switch ch := s.ch; {
+	case s.nextVal:
+		lit = s.scanValString()
+		tok = token.STRING
+		s.nextVal = false
+	case isLetter(ch):
+		lit = s.scanIdentifier()
+		tok = token.IDENT
+	default:
+		s.next() // always make progress
+		switch ch {
+		case -1:
+			tok = token.EOF
+		case '\n':
+			tok = token.EOL
+		case '"':
+			tok = token.STRING
+			lit = s.scanString()
+		case '[':
+			tok = token.LBRACK
+		case ']':
+			tok = token.RBRACK
+		case ';', '#':
+			// comment
+			lit = s.scanComment()
+			if s.mode&ScanComments == 0 {
+				// skip comment
+				goto scanAgain
+			}
+			tok = token.COMMENT
+		case '=':
+			tok = token.ASSIGN
+			s.nextVal = true
+		default:
+			s.error(s.file.Offset(pos), fmt.Sprintf("illegal character %#U", ch))
+			tok = token.ILLEGAL
+			lit = string(ch)
+		}
+	}
+
+	return
+}
diff --git a/vendor/github.com/src-d/gcfg/set.go b/vendor/github.com/src-d/gcfg/set.go
new file mode 100644
index 0000000000..771258f0ef
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/set.go
@@ -0,0 +1,332 @@
+package gcfg
+
+import (
+	"bytes"
+	"encoding/gob"
+	"fmt"
+	"math/big"
+	"reflect"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/src-d/gcfg/types"
+	"gopkg.in/warnings.v0"
+)
+
+type tag struct {
+	ident   string
+	intMode string
+}
+
+func newTag(ts string) tag {
+	t := tag{}
+	s := strings.Split(ts, ",")
+	t.ident = s[0]
+	for _, tse := range s[1:] {
+		if strings.HasPrefix(tse, "int=") {
+			t.intMode = tse[len("int="):]
+		}
+	}
+	return t
+}
+
+func fieldFold(v reflect.Value, name string) (reflect.Value, tag) {
+	var n string
+	r0, _ := utf8.DecodeRuneInString(name)
+	if unicode.IsLetter(r0) && !unicode.IsLower(r0) && !unicode.IsUpper(r0) {
+		n = "X"
+	}
+	n += strings.Replace(name, "-", "_", -1)
+	f, ok := v.Type().FieldByNameFunc(func(fieldName string) bool {
+		if !v.FieldByName(fieldName).CanSet() {
+			return false
+		}
+		f, _ := v.Type().FieldByName(fieldName)
+		t := newTag(f.Tag.Get("gcfg"))
+		if t.ident != "" {
+			return strings.EqualFold(t.ident, name)
+		}
+		return strings.EqualFold(n, fieldName)
+	})
+	if !ok {
+		return reflect.Value{}, tag{}
+	}
+	return v.FieldByName(f.Name), newTag(f.Tag.Get("gcfg"))
+}
+
+type setter func(destp interface{}, blank bool, val string, t tag) error
+
+var errUnsupportedType = fmt.Errorf("unsupported type")
+var errBlankUnsupported = fmt.Errorf("blank value not supported for type")
+
+var setters = []setter{
+	typeSetter, textUnmarshalerSetter, kindSetter, scanSetter,
+}
+
+func textUnmarshalerSetter(d interface{}, blank bool, val string, t tag) error {
+	dtu, ok := d.(textUnmarshaler)
+	if !ok {
+		return errUnsupportedType
+	}
+	if blank {
+		return errBlankUnsupported
+	}
+	return dtu.UnmarshalText([]byte(val))
+}
+
+func boolSetter(d interface{}, blank bool, val string, t tag) error {
+	if blank {
+		reflect.ValueOf(d).Elem().Set(reflect.ValueOf(true))
+		return nil
+	}
+	b, err := types.ParseBool(val)
+	if err == nil {
+		reflect.ValueOf(d).Elem().Set(reflect.ValueOf(b))
+	}
+	return err
+}
+
+func intMode(mode string) types.IntMode {
+	var m types.IntMode
+	if strings.ContainsAny(mode, "dD") {
+		m |= types.Dec
+	}
+	if strings.ContainsAny(mode, "hH") {
+		m |= types.Hex
+	}
+	if strings.ContainsAny(mode, "oO") {
+		m |= types.Oct
+	}
+	return m
+}
+
+var typeModes = map[reflect.Type]types.IntMode{
+	reflect.TypeOf(int(0)):    types.Dec | types.Hex,
+	reflect.TypeOf(int8(0)):   types.Dec | types.Hex,
+	reflect.TypeOf(int16(0)):  types.Dec | types.Hex,
+	reflect.TypeOf(int32(0)):  types.Dec | types.Hex,
+	reflect.TypeOf(int64(0)):  types.Dec | types.Hex,
+	reflect.TypeOf(uint(0)):   types.Dec | types.Hex,
+	reflect.TypeOf(uint8(0)):  types.Dec | types.Hex,
+	reflect.TypeOf(uint16(0)): types.Dec | types.Hex,
+	reflect.TypeOf(uint32(0)): types.Dec | types.Hex,
+	reflect.TypeOf(uint64(0)): types.Dec | types.Hex,
+	// use default mode (allow dec/hex/oct) for uintptr type
+	reflect.TypeOf(big.Int{}): types.Dec | types.Hex,
+}
+
+func intModeDefault(t reflect.Type) types.IntMode {
+	m, ok := typeModes[t]
+	if !ok {
+		m = types.Dec | types.Hex | types.Oct
+	}
+	return m
+}
+
+func intSetter(d interface{}, blank bool, val string, t tag) error {
+	if blank {
+		return errBlankUnsupported
+	}
+	mode := intMode(t.intMode)
+	if mode == 0 {
+		mode = intModeDefault(reflect.TypeOf(d).Elem())
+	}
+	return types.ParseInt(d, val, mode)
+}
+
+func stringSetter(d interface{}, blank bool, val string, t tag) error {
+	if blank {
+		return errBlankUnsupported
+	}
+	dsp, ok := d.(*string)
+	if !ok {
+		return errUnsupportedType
+	}
+	*dsp = val
+	return nil
+}
+
+var kindSetters = map[reflect.Kind]setter{
+	reflect.String:  stringSetter,
+	reflect.Bool:    boolSetter,
+	reflect.Int:     intSetter,
+	reflect.Int8:    intSetter,
+	reflect.Int16:   intSetter,
+	reflect.Int32:   intSetter,
+	reflect.Int64:   intSetter,
+	reflect.Uint:    intSetter,
+	reflect.Uint8:   intSetter,
+	reflect.Uint16:  intSetter,
+	reflect.Uint32:  intSetter,
+	reflect.Uint64:  intSetter,
+	reflect.Uintptr: intSetter,
+}
+
+var typeSetters = map[reflect.Type]setter{
+	reflect.TypeOf(big.Int{}): intSetter,
+}
+
+func typeSetter(d interface{}, blank bool, val string, tt tag) error {
+	t := reflect.ValueOf(d).Type().Elem()
+	setter, ok := typeSetters[t]
+	if !ok {
+		return errUnsupportedType
+	}
+	return setter(d, blank, val, tt)
+}
+
+func kindSetter(d interface{}, blank bool, val string, tt tag) error {
+	k := reflect.ValueOf(d).Type().Elem().Kind()
+	setter, ok := kindSetters[k]
+	if !ok {
+		return errUnsupportedType
+	}
+	return setter(d, blank, val, tt)
+}
+
+func scanSetter(d interface{}, blank bool, val string, tt tag) error {
+	if blank {
+		return errBlankUnsupported
+	}
+	return types.ScanFully(d, val, 'v')
+}
+
+func newValue(c *warnings.Collector, sect string, vCfg reflect.Value,
+	vType reflect.Type) (reflect.Value, error) {
+	//
+	pv := reflect.New(vType)
+	dfltName := "default-" + sect
+	dfltField, _ := fieldFold(vCfg, dfltName)
+	var err error
+	if dfltField.IsValid() {
+		b := bytes.NewBuffer(nil)
+		ge := gob.NewEncoder(b)
+		if err = c.Collect(ge.EncodeValue(dfltField)); err != nil {
+			return pv, err
+		}
+		gd := gob.NewDecoder(bytes.NewReader(b.Bytes()))
+		if err = c.Collect(gd.DecodeValue(pv.Elem())); err != nil {
+			return pv, err
+		}
+	}
+	return pv, nil
+}
+
+func set(c *warnings.Collector, cfg interface{}, sect, sub, name string,
+	 value string, blankValue bool, subsectPass bool) error {
+	//
+	vPCfg := reflect.ValueOf(cfg)
+	if vPCfg.Kind() != reflect.Ptr || vPCfg.Elem().Kind() != reflect.Struct {
+		panic(fmt.Errorf("config must be a pointer to a struct"))
+	}
+	vCfg := vPCfg.Elem()
+	vSect, _ := fieldFold(vCfg, sect)
+	if !vSect.IsValid() {
+		err := extraData{section: sect}
+		return c.Collect(err)
+	}
+	isSubsect := vSect.Kind() == reflect.Map
+	if subsectPass != isSubsect {
+		return nil
+	}
+	if isSubsect {
+		vst := vSect.Type()
+		if vst.Key().Kind() != reflect.String ||
+			vst.Elem().Kind() != reflect.Ptr ||
+			vst.Elem().Elem().Kind() != reflect.Struct {
+			panic(fmt.Errorf("map field for section must have string keys and "+
+				" pointer-to-struct values: section %q", sect))
+		}
+		if vSect.IsNil() {
+			vSect.Set(reflect.MakeMap(vst))
+		}
+		k := reflect.ValueOf(sub)
+		pv := vSect.MapIndex(k)
+		if !pv.IsValid() {
+			vType := vSect.Type().Elem().Elem()
+			var err error
+			if pv, err = newValue(c, sect, vCfg, vType); err != nil {
+				return err
+			}
+			vSect.SetMapIndex(k, pv)
+		}
+		vSect = pv.Elem()
+	} else if vSect.Kind() != reflect.Struct {
+		panic(fmt.Errorf("field for section must be a map or a struct: "+
+			"section %q", sect))
+	} else if sub != "" {
+		err := extraData{section: sect, subsection: &sub}
+		return c.Collect(err)
+	}
+	// Empty name is a special value, meaning that only the
+	// section/subsection object is to be created, with no values set.
+	if name == "" {
+		return nil
+	}
+	vVar, t := fieldFold(vSect, name)
+	if !vVar.IsValid() {
+		var err error
+		if isSubsect {
+			err = extraData{section: sect, subsection: &sub, variable: &name}
+		} else {
+			err = extraData{section: sect, variable: &name}
+		}
+		return c.Collect(err)
+	}
+	// vVal is either single-valued var, or newly allocated value within multi-valued var
+	var vVal reflect.Value
+	// multi-value if unnamed slice type
+	isMulti := vVar.Type().Name() == "" && vVar.Kind() == reflect.Slice ||
+		vVar.Type().Name() == "" && vVar.Kind() == reflect.Ptr && vVar.Type().Elem().Name() == "" && vVar.Type().Elem().Kind() == reflect.Slice
+	if isMulti && vVar.Kind() == reflect.Ptr {
+		if vVar.IsNil() {
+			vVar.Set(reflect.New(vVar.Type().Elem()))
+		}
+		vVar = vVar.Elem()
+	}
+	if isMulti && blankValue {
+		vVar.Set(reflect.Zero(vVar.Type()))
+		return nil
+	}
+	if isMulti {
+		vVal = reflect.New(vVar.Type().Elem()).Elem()
+	} else {
+		vVal = vVar
+	}
+	isDeref := vVal.Type().Name() == "" && vVal.Type().Kind() == reflect.Ptr
+	isNew := isDeref && vVal.IsNil()
+	// vAddr is address of value to set (dereferenced & allocated as needed)
+	var vAddr reflect.Value
+	switch {
+	case isNew:
+		vAddr = reflect.New(vVal.Type().Elem())
+	case isDeref && !isNew:
+		vAddr = vVal
+	default:
+		vAddr = vVal.Addr()
+	}
+	vAddrI := vAddr.Interface()
+	err, ok := error(nil), false
+	for _, s := range setters {
+		err = s(vAddrI, blankValue, value, t)
+		if err == nil {
+			ok = true
+			break
+		}
+		if err != errUnsupportedType {
+			return err
+		}
+	}
+	if !ok {
+		// in case all setters returned errUnsupportedType
+		return err
+	}
+	if isNew { // set reference if it was dereferenced and newly allocated
+		vVal.Set(vAddr)
+	}
+	if isMulti { // append if multi-valued
+		vVar.Set(reflect.Append(vVar, vVal))
+	}
+	return nil
+}
diff --git a/vendor/github.com/src-d/gcfg/token/position.go b/vendor/github.com/src-d/gcfg/token/position.go
new file mode 100644
index 0000000000..fc45c1e769
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/token/position.go
@@ -0,0 +1,435 @@
+// Copyright 2010 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.
+
+// TODO(gri) consider making this a separate package outside the go directory.
+
+package token
+
+import (
+	"fmt"
+	"sort"
+	"sync"
+)
+
+// -----------------------------------------------------------------------------
+// Positions
+
+// Position describes an arbitrary source position
+// including the file, line, and column location.
+// A Position is valid if the line number is > 0.
+//
+type Position struct {
+	Filename string // filename, if any
+	Offset   int    // offset, starting at 0
+	Line     int    // line number, starting at 1
+	Column   int    // column number, starting at 1 (character count)
+}
+
+// IsValid returns true if the position is valid.
+func (pos *Position) IsValid() bool { return pos.Line > 0 }
+
+// String returns a string in one of several forms:
+//
+//	file:line:column    valid position with file name
+//	line:column         valid position without file name
+//	file                invalid position with file name
+//	-                   invalid position without file name
+//
+func (pos Position) String() string {
+	s := pos.Filename
+	if pos.IsValid() {
+		if s != "" {
+			s += ":"
+		}
+		s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
+	}
+	if s == "" {
+		s = "-"
+	}
+	return s
+}
+
+// Pos is a compact encoding of a source position within a file set.
+// It can be converted into a Position for a more convenient, but much
+// larger, representation.
+//
+// The Pos value for a given file is a number in the range [base, base+size],
+// where base and size are specified when adding the file to the file set via
+// AddFile.
+//
+// To create the Pos value for a specific source offset, first add
+// the respective file to the current file set (via FileSet.AddFile)
+// and then call File.Pos(offset) for that file. Given a Pos value p
+// for a specific file set fset, the corresponding Position value is
+// obtained by calling fset.Position(p).
+//
+// Pos values can be compared directly with the usual comparison operators:
+// If two Pos values p and q are in the same file, comparing p and q is
+// equivalent to comparing the respective source file offsets. If p and q
+// are in different files, p < q is true if the file implied by p was added
+// to the respective file set before the file implied by q.
+//
+type Pos int
+
+// The zero value for Pos is NoPos; there is no file and line information
+// associated with it, and NoPos().IsValid() is false. NoPos is always
+// smaller than any other Pos value. The corresponding Position value
+// for NoPos is the zero value for Position.
+//
+const NoPos Pos = 0
+
+// IsValid returns true if the position is valid.
+func (p Pos) IsValid() bool {
+	return p != NoPos
+}
+
+// -----------------------------------------------------------------------------
+// File
+
+// A File is a handle for a file belonging to a FileSet.
+// A File has a name, size, and line offset table.
+//
+type File struct {
+	set  *FileSet
+	name string // file name as provided to AddFile
+	base int    // Pos value range for this file is [base...base+size]
+	size int    // file size as provided to AddFile
+
+	// lines and infos are protected by set.mutex
+	lines []int
+	infos []lineInfo
+}
+
+// Name returns the file name of file f as registered with AddFile.
+func (f *File) Name() string {
+	return f.name
+}
+
+// Base returns the base offset of file f as registered with AddFile.
+func (f *File) Base() int {
+	return f.base
+}
+
+// Size returns the size of file f as registered with AddFile.
+func (f *File) Size() int {
+	return f.size
+}
+
+// LineCount returns the number of lines in file f.
+func (f *File) LineCount() int {
+	f.set.mutex.RLock()
+	n := len(f.lines)
+	f.set.mutex.RUnlock()
+	return n
+}
+
+// AddLine adds the line offset for a new line.
+// The line offset must be larger than the offset for the previous line
+// and smaller than the file size; otherwise the line offset is ignored.
+//
+func (f *File) AddLine(offset int) {
+	f.set.mutex.Lock()
+	if i := len(f.lines); (i == 0 || f.lines[i-1] < offset) && offset < f.size {
+		f.lines = append(f.lines, offset)
+	}
+	f.set.mutex.Unlock()
+}
+
+// SetLines sets the line offsets for a file and returns true if successful.
+// The line offsets are the offsets of the first character of each line;
+// for instance for the content "ab\nc\n" the line offsets are {0, 3}.
+// An empty file has an empty line offset table.
+// Each line offset must be larger than the offset for the previous line
+// and smaller than the file size; otherwise SetLines fails and returns
+// false.
+//
+func (f *File) SetLines(lines []int) bool {
+	// verify validity of lines table
+	size := f.size
+	for i, offset := range lines {
+		if i > 0 && offset <= lines[i-1] || size <= offset {
+			return false
+		}
+	}
+
+	// set lines table
+	f.set.mutex.Lock()
+	f.lines = lines
+	f.set.mutex.Unlock()
+	return true
+}
+
+// SetLinesForContent sets the line offsets for the given file content.
+func (f *File) SetLinesForContent(content []byte) {
+	var lines []int
+	line := 0
+	for offset, b := range content {
+		if line >= 0 {
+			lines = append(lines, line)
+		}
+		line = -1
+		if b == '\n' {
+			line = offset + 1
+		}
+	}
+
+	// set lines table
+	f.set.mutex.Lock()
+	f.lines = lines
+	f.set.mutex.Unlock()
+}
+
+// A lineInfo object describes alternative file and line number
+// information (such as provided via a //line comment in a .go
+// file) for a given file offset.
+type lineInfo struct {
+	// fields are exported to make them accessible to gob
+	Offset   int
+	Filename string
+	Line     int
+}
+
+// AddLineInfo adds alternative file and line number information for
+// a given file offset. The offset must be larger than the offset for
+// the previously added alternative line info and smaller than the
+// file size; otherwise the information is ignored.
+//
+// AddLineInfo is typically used to register alternative position
+// information for //line filename:line comments in source files.
+//
+func (f *File) AddLineInfo(offset int, filename string, line int) {
+	f.set.mutex.Lock()
+	if i := len(f.infos); i == 0 || f.infos[i-1].Offset < offset && offset < f.size {
+		f.infos = append(f.infos, lineInfo{offset, filename, line})
+	}
+	f.set.mutex.Unlock()
+}
+
+// Pos returns the Pos value for the given file offset;
+// the offset must be <= f.Size().
+// f.Pos(f.Offset(p)) == p.
+//
+func (f *File) Pos(offset int) Pos {
+	if offset > f.size {
+		panic("illegal file offset")
+	}
+	return Pos(f.base + offset)
+}
+
+// Offset returns the offset for the given file position p;
+// p must be a valid Pos value in that file.
+// f.Offset(f.Pos(offset)) == offset.
+//
+func (f *File) Offset(p Pos) int {
+	if int(p) < f.base || int(p) > f.base+f.size {
+		panic("illegal Pos value")
+	}
+	return int(p) - f.base
+}
+
+// Line returns the line number for the given file position p;
+// p must be a Pos value in that file or NoPos.
+//
+func (f *File) Line(p Pos) int {
+	// TODO(gri) this can be implemented much more efficiently
+	return f.Position(p).Line
+}
+
+func searchLineInfos(a []lineInfo, x int) int {
+	return sort.Search(len(a), func(i int) bool { return a[i].Offset > x }) - 1
+}
+
+// info returns the file name, line, and column number for a file offset.
+func (f *File) info(offset int) (filename string, line, column int) {
+	filename = f.name
+	if i := searchInts(f.lines, offset); i >= 0 {
+		line, column = i+1, offset-f.lines[i]+1
+	}
+	if len(f.infos) > 0 {
+		// almost no files have extra line infos
+		if i := searchLineInfos(f.infos, offset); i >= 0 {
+			alt := &f.infos[i]
+			filename = alt.Filename
+			if i := searchInts(f.lines, alt.Offset); i >= 0 {
+				line += alt.Line - i - 1
+			}
+		}
+	}
+	return
+}
+
+func (f *File) position(p Pos) (pos Position) {
+	offset := int(p) - f.base
+	pos.Offset = offset
+	pos.Filename, pos.Line, pos.Column = f.info(offset)
+	return
+}
+
+// Position returns the Position value for the given file position p;
+// p must be a Pos value in that file or NoPos.
+//
+func (f *File) Position(p Pos) (pos Position) {
+	if p != NoPos {
+		if int(p) < f.base || int(p) > f.base+f.size {
+			panic("illegal Pos value")
+		}
+		pos = f.position(p)
+	}
+	return
+}
+
+// -----------------------------------------------------------------------------
+// FileSet
+
+// A FileSet represents a set of source files.
+// Methods of file sets are synchronized; multiple goroutines
+// may invoke them concurrently.
+//
+type FileSet struct {
+	mutex sync.RWMutex // protects the file set
+	base  int          // base offset for the next file
+	files []*File      // list of files in the order added to the set
+	last  *File        // cache of last file looked up
+}
+
+// NewFileSet creates a new file set.
+func NewFileSet() *FileSet {
+	s := new(FileSet)
+	s.base = 1 // 0 == NoPos
+	return s
+}
+
+// Base returns the minimum base offset that must be provided to
+// AddFile when adding the next file.
+//
+func (s *FileSet) Base() int {
+	s.mutex.RLock()
+	b := s.base
+	s.mutex.RUnlock()
+	return b
+
+}
+
+// AddFile adds a new file with a given filename, base offset, and file size
+// to the file set s and returns the file. Multiple files may have the same
+// name. The base offset must not be smaller than the FileSet's Base(), and
+// size must not be negative.
+//
+// Adding the file will set the file set's Base() value to base + size + 1
+// as the minimum base value for the next file. The following relationship
+// exists between a Pos value p for a given file offset offs:
+//
+//	int(p) = base + offs
+//
+// with offs in the range [0, size] and thus p in the range [base, base+size].
+// For convenience, File.Pos may be used to create file-specific position
+// values from a file offset.
+//
+func (s *FileSet) AddFile(filename string, base, size int) *File {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	if base < s.base || size < 0 {
+		panic("illegal base or size")
+	}
+	// base >= s.base && size >= 0
+	f := &File{s, filename, base, size, []int{0}, nil}
+	base += size + 1 // +1 because EOF also has a position
+	if base < 0 {
+		panic("token.Pos offset overflow (> 2G of source code in file set)")
+	}
+	// add the file to the file set
+	s.base = base
+	s.files = append(s.files, f)
+	s.last = f
+	return f
+}
+
+// Iterate calls f for the files in the file set in the order they were added
+// until f returns false.
+//
+func (s *FileSet) Iterate(f func(*File) bool) {
+	for i := 0; ; i++ {
+		var file *File
+		s.mutex.RLock()
+		if i < len(s.files) {
+			file = s.files[i]
+		}
+		s.mutex.RUnlock()
+		if file == nil || !f(file) {
+			break
+		}
+	}
+}
+
+func searchFiles(a []*File, x int) int {
+	return sort.Search(len(a), func(i int) bool { return a[i].base > x }) - 1
+}
+
+func (s *FileSet) file(p Pos) *File {
+	// common case: p is in last file
+	if f := s.last; f != nil && f.base <= int(p) && int(p) <= f.base+f.size {
+		return f
+	}
+	// p is not in last file - search all files
+	if i := searchFiles(s.files, int(p)); i >= 0 {
+		f := s.files[i]
+		// f.base <= int(p) by definition of searchFiles
+		if int(p) <= f.base+f.size {
+			s.last = f
+			return f
+		}
+	}
+	return nil
+}
+
+// File returns the file that contains the position p.
+// If no such file is found (for instance for p == NoPos),
+// the result is nil.
+//
+func (s *FileSet) File(p Pos) (f *File) {
+	if p != NoPos {
+		s.mutex.RLock()
+		f = s.file(p)
+		s.mutex.RUnlock()
+	}
+	return
+}
+
+// Position converts a Pos in the fileset into a general Position.
+func (s *FileSet) Position(p Pos) (pos Position) {
+	if p != NoPos {
+		s.mutex.RLock()
+		if f := s.file(p); f != nil {
+			pos = f.position(p)
+		}
+		s.mutex.RUnlock()
+	}
+	return
+}
+
+// -----------------------------------------------------------------------------
+// Helper functions
+
+func searchInts(a []int, x int) int {
+	// This function body is a manually inlined version of:
+	//
+	//   return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1
+	//
+	// With better compiler optimizations, this may not be needed in the
+	// future, but at the moment this change improves the go/printer
+	// benchmark performance by ~30%. This has a direct impact on the
+	// speed of gofmt and thus seems worthwhile (2011-04-29).
+	// TODO(gri): Remove this when compilers have caught up.
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2 // avoid overflow when computing h
+		// i ≤ h < j
+		if a[h] <= x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i - 1
+}
diff --git a/vendor/github.com/src-d/gcfg/token/serialize.go b/vendor/github.com/src-d/gcfg/token/serialize.go
new file mode 100644
index 0000000000..4adc8f9e33
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/token/serialize.go
@@ -0,0 +1,56 @@
+// Copyright 2011 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 token
+
+type serializedFile struct {
+	// fields correspond 1:1 to fields with same (lower-case) name in File
+	Name  string
+	Base  int
+	Size  int
+	Lines []int
+	Infos []lineInfo
+}
+
+type serializedFileSet struct {
+	Base  int
+	Files []serializedFile
+}
+
+// Read calls decode to deserialize a file set into s; s must not be nil.
+func (s *FileSet) Read(decode func(interface{}) error) error {
+	var ss serializedFileSet
+	if err := decode(&ss); err != nil {
+		return err
+	}
+
+	s.mutex.Lock()
+	s.base = ss.Base
+	files := make([]*File, len(ss.Files))
+	for i := 0; i < len(ss.Files); i++ {
+		f := &ss.Files[i]
+		files[i] = &File{s, f.Name, f.Base, f.Size, f.Lines, f.Infos}
+	}
+	s.files = files
+	s.last = nil
+	s.mutex.Unlock()
+
+	return nil
+}
+
+// Write calls encode to serialize the file set s.
+func (s *FileSet) Write(encode func(interface{}) error) error {
+	var ss serializedFileSet
+
+	s.mutex.Lock()
+	ss.Base = s.base
+	files := make([]serializedFile, len(s.files))
+	for i, f := range s.files {
+		files[i] = serializedFile{f.name, f.base, f.size, f.lines, f.infos}
+	}
+	ss.Files = files
+	s.mutex.Unlock()
+
+	return encode(ss)
+}
diff --git a/vendor/github.com/src-d/gcfg/token/token.go b/vendor/github.com/src-d/gcfg/token/token.go
new file mode 100644
index 0000000000..b3c7c83fa9
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/token/token.go
@@ -0,0 +1,83 @@
+// Copyright 2009 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 token defines constants representing the lexical tokens of the gcfg
+// configuration syntax and basic operations on tokens (printing, predicates).
+//
+// Note that the API for the token package may change to accommodate new
+// features or implementation changes in gcfg.
+//
+package token
+
+import "strconv"
+
+// Token is the set of lexical tokens of the gcfg configuration syntax.
+type Token int
+
+// The list of tokens.
+const (
+	// Special tokens
+	ILLEGAL Token = iota
+	EOF
+	COMMENT
+
+	literal_beg
+	// Identifiers and basic type literals
+	// (these tokens stand for classes of literals)
+	IDENT  // section-name, variable-name
+	STRING // "subsection-name", variable value
+	literal_end
+
+	operator_beg
+	// Operators and delimiters
+	ASSIGN // =
+	LBRACK // [
+	RBRACK // ]
+	EOL    // \n
+	operator_end
+)
+
+var tokens = [...]string{
+	ILLEGAL: "ILLEGAL",
+
+	EOF:     "EOF",
+	COMMENT: "COMMENT",
+
+	IDENT:  "IDENT",
+	STRING: "STRING",
+
+	ASSIGN: "=",
+	LBRACK: "[",
+	RBRACK: "]",
+	EOL:    "\n",
+}
+
+// String returns the string corresponding to the token tok.
+// For operators and delimiters, the string is the actual token character
+// sequence (e.g., for the token ASSIGN, the string is "="). For all other
+// tokens the string corresponds to the token constant name (e.g. for the
+// token IDENT, the string is "IDENT").
+//
+func (tok Token) String() string {
+	s := ""
+	if 0 <= tok && tok < Token(len(tokens)) {
+		s = tokens[tok]
+	}
+	if s == "" {
+		s = "token(" + strconv.Itoa(int(tok)) + ")"
+	}
+	return s
+}
+
+// Predicates
+
+// IsLiteral returns true for tokens corresponding to identifiers
+// and basic type literals; it returns false otherwise.
+//
+func (tok Token) IsLiteral() bool { return literal_beg < tok && tok < literal_end }
+
+// IsOperator returns true for tokens corresponding to operators and
+// delimiters; it returns false otherwise.
+//
+func (tok Token) IsOperator() bool { return operator_beg < tok && tok < operator_end }
diff --git a/vendor/github.com/src-d/gcfg/types/bool.go b/vendor/github.com/src-d/gcfg/types/bool.go
new file mode 100644
index 0000000000..8dcae0d8cf
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/types/bool.go
@@ -0,0 +1,23 @@
+package types
+
+// BoolValues defines the name and value mappings for ParseBool.
+var BoolValues = map[string]interface{}{
+	"true": true, "yes": true, "on": true, "1": true,
+	"false": false, "no": false, "off": false, "0": false,
+}
+
+var boolParser = func() *EnumParser {
+	ep := &EnumParser{}
+	ep.AddVals(BoolValues)
+	return ep
+}()
+
+// ParseBool parses bool values according to the definitions in BoolValues.
+// Parsing is case-insensitive.
+func ParseBool(s string) (bool, error) {
+	v, err := boolParser.Parse(s)
+	if err != nil {
+		return false, err
+	}
+	return v.(bool), nil
+}
diff --git a/vendor/github.com/src-d/gcfg/types/doc.go b/vendor/github.com/src-d/gcfg/types/doc.go
new file mode 100644
index 0000000000..9f9c345f6e
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/types/doc.go
@@ -0,0 +1,4 @@
+// Package types defines helpers for type conversions.
+//
+// The API for this package is not finalized yet.
+package types
diff --git a/vendor/github.com/src-d/gcfg/types/enum.go b/vendor/github.com/src-d/gcfg/types/enum.go
new file mode 100644
index 0000000000..1a0c7ef453
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/types/enum.go
@@ -0,0 +1,44 @@
+package types
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// EnumParser parses "enum" values; i.e. a predefined set of strings to
+// predefined values.
+type EnumParser struct {
+	Type      string // type name; if not set, use type of first value added
+	CaseMatch bool   // if true, matching of strings is case-sensitive
+	// PrefixMatch bool
+	vals map[string]interface{}
+}
+
+// AddVals adds strings and values to an EnumParser.
+func (ep *EnumParser) AddVals(vals map[string]interface{}) {
+	if ep.vals == nil {
+		ep.vals = make(map[string]interface{})
+	}
+	for k, v := range vals {
+		if ep.Type == "" {
+			ep.Type = reflect.TypeOf(v).Name()
+		}
+		if !ep.CaseMatch {
+			k = strings.ToLower(k)
+		}
+		ep.vals[k] = v
+	}
+}
+
+// Parse parses the string and returns the value or an error.
+func (ep EnumParser) Parse(s string) (interface{}, error) {
+	if !ep.CaseMatch {
+		s = strings.ToLower(s)
+	}
+	v, ok := ep.vals[s]
+	if !ok {
+		return false, fmt.Errorf("failed to parse %s %#q", ep.Type, s)
+	}
+	return v, nil
+}
diff --git a/vendor/github.com/src-d/gcfg/types/int.go b/vendor/github.com/src-d/gcfg/types/int.go
new file mode 100644
index 0000000000..af7e75c125
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/types/int.go
@@ -0,0 +1,86 @@
+package types
+
+import (
+	"fmt"
+	"strings"
+)
+
+// An IntMode is a mode for parsing integer values, representing a set of
+// accepted bases.
+type IntMode uint8
+
+// IntMode values for ParseInt; can be combined using binary or.
+const (
+	Dec IntMode = 1 << iota
+	Hex
+	Oct
+)
+
+// String returns a string representation of IntMode; e.g. `IntMode(Dec|Hex)`.
+func (m IntMode) String() string {
+	var modes []string
+	if m&Dec != 0 {
+		modes = append(modes, "Dec")
+	}
+	if m&Hex != 0 {
+		modes = append(modes, "Hex")
+	}
+	if m&Oct != 0 {
+		modes = append(modes, "Oct")
+	}
+	return "IntMode(" + strings.Join(modes, "|") + ")"
+}
+
+var errIntAmbig = fmt.Errorf("ambiguous integer value; must include '0' prefix")
+
+func prefix0(val string) bool {
+	return strings.HasPrefix(val, "0") || strings.HasPrefix(val, "-0")
+}
+
+func prefix0x(val string) bool {
+	return strings.HasPrefix(val, "0x") || strings.HasPrefix(val, "-0x")
+}
+
+// ParseInt parses val using mode into intptr, which must be a pointer to an
+// integer kind type. Non-decimal value require prefix `0` or `0x` in the cases
+// when mode permits ambiguity of base; otherwise the prefix can be omitted.
+func ParseInt(intptr interface{}, val string, mode IntMode) error {
+	val = strings.TrimSpace(val)
+	verb := byte(0)
+	switch mode {
+	case Dec:
+		verb = 'd'
+	case Dec + Hex:
+		if prefix0x(val) {
+			verb = 'v'
+		} else {
+			verb = 'd'
+		}
+	case Dec + Oct:
+		if prefix0(val) && !prefix0x(val) {
+			verb = 'v'
+		} else {
+			verb = 'd'
+		}
+	case Dec + Hex + Oct:
+		verb = 'v'
+	case Hex:
+		if prefix0x(val) {
+			verb = 'v'
+		} else {
+			verb = 'x'
+		}
+	case Oct:
+		verb = 'o'
+	case Hex + Oct:
+		if prefix0(val) {
+			verb = 'v'
+		} else {
+			return errIntAmbig
+		}
+	}
+	if verb == 0 {
+		panic("unsupported mode")
+	}
+	return ScanFully(intptr, val, verb)
+}
diff --git a/vendor/github.com/src-d/gcfg/types/scan.go b/vendor/github.com/src-d/gcfg/types/scan.go
new file mode 100644
index 0000000000..db2f6ed3ca
--- /dev/null
+++ b/vendor/github.com/src-d/gcfg/types/scan.go
@@ -0,0 +1,23 @@
+package types
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+)
+
+// ScanFully uses fmt.Sscanf with verb to fully scan val into ptr.
+func ScanFully(ptr interface{}, val string, verb byte) error {
+	t := reflect.ValueOf(ptr).Elem().Type()
+	// attempt to read extra bytes to make sure the value is consumed
+	var b []byte
+	n, err := fmt.Sscanf(val, "%"+string(verb)+"%s", ptr, &b)
+	switch {
+	case n < 1 || n == 1 && err != io.EOF:
+		return fmt.Errorf("failed to parse %q as %v: %v", val, t, err)
+	case n > 1:
+		return fmt.Errorf("failed to parse %q as %v: extra characters %q", val, t, string(b))
+	}
+	// n == 1 && err == io.EOF
+	return nil
+}