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 :)

vendor/gopkg.in/warnings.v0/LICENSE

@@ -0,0 +1,24 @@
+Copyright (c) 2016 Péter Surányi.
+
+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.
+
+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.

vendor/gopkg.in/warnings.v0/warnings.go

@@ -0,0 +1,194 @@
+// Package warnings implements error handling with non-fatal errors (warnings).
+//
+// A recurring pattern in Go programming is the following:
+//
+//  func myfunc(params) error {
+//      if err := doSomething(...); err != nil {
+//          return err
+//      }
+//      if err := doSomethingElse(...); err != nil {
+//          return err
+//      }
+//      if ok := doAnotherThing(...); !ok {
+//          return errors.New("my error")
+//      }
+//      ...
+//      return nil
+//  }
+//
+// This pattern allows interrupting the flow on any received error. But what if
+// there are errors that should be noted but still not fatal, for which the flow
+// should not be interrupted? Implementing such logic at each if statement would
+// make the code complex and the flow much harder to follow.
+//
+// Package warnings provides the Collector type and a clean and simple pattern
+// for achieving such logic. The Collector takes care of deciding when to break
+// the flow and when to continue, collecting any non-fatal errors (warnings)
+// along the way. The only requirement is that fatal and non-fatal errors can be
+// distinguished programmatically; that is a function such as
+//
+//  IsFatal(error) bool
+//
+// must be implemented. The following is an example of what the above snippet
+// could look like using the warnings package:
+//
+//  import "gopkg.in/warnings.v0"
+//
+//  func isFatal(err error) bool {
+//      _, ok := err.(WarningType)
+//      return !ok
+//  }
+//
+//  func myfunc(params) error {
+//      c := warnings.NewCollector(isFatal)
+//      c.FatalWithWarnings = true
+//      if err := c.Collect(doSomething()); err != nil {
+//          return err
+//      }
+//      if err := c.Collect(doSomethingElse(...)); err != nil {
+//          return err
+//      }
+//      if ok := doAnotherThing(...); !ok {
+//          if err := c.Collect(errors.New("my error")); err != nil {
+//              return err
+//          }
+//      }
+//      ...
+//      return c.Done()
+//  }
+//
+// For an example of a non-trivial code base using this library, see
+// gopkg.in/gcfg.v1
+//
+// Rules for using warnings
+//
+//  - ensure that warnings are programmatically distinguishable from fatal
+//    errors (i.e. implement an isFatal function and any necessary error types)
+//  - ensure that there is a single Collector instance for a call of each
+//    exported function
+//  - ensure that all errors (fatal or warning) are fed through Collect
+//  - ensure that every time an error is returned, it is one returned by a
+//    Collector (from Collect or Done)
+//  - ensure that Collect is never called after Done
+//
+// TODO
+//
+//  - optionally limit the number of warnings (e.g. stop after 20 warnings) (?)
+//  - consider interaction with contexts
+//  - go vet-style invocations verifier
+//  - semi-automatic code converter
+//
+package warnings // import "gopkg.in/warnings.v0"
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// List holds a collection of warnings and optionally one fatal error.
+type List struct {
+	Warnings []error
+	Fatal    error
+}
+
+// Error implements the error interface.
+func (l List) Error() string {
+	b := bytes.NewBuffer(nil)
+	if l.Fatal != nil {
+		fmt.Fprintln(b, "fatal:")
+		fmt.Fprintln(b, l.Fatal)
+	}
+	switch len(l.Warnings) {
+	case 0:
+	// nop
+	case 1:
+		fmt.Fprintln(b, "warning:")
+	default:
+		fmt.Fprintln(b, "warnings:")
+	}
+	for _, err := range l.Warnings {
+		fmt.Fprintln(b, err)
+	}
+	return b.String()
+}
+
+// A Collector collects errors up to the first fatal error.
+type Collector struct {
+	// IsFatal distinguishes between warnings and fatal errors.
+	IsFatal func(error) bool
+	// FatalWithWarnings set to true means that a fatal error is returned as
+	// a List together with all warnings so far. The default behavior is to
+	// only return the fatal error and discard any warnings that have been
+	// collected.
+	FatalWithWarnings bool
+
+	l    List
+	done bool
+}
+
+// NewCollector returns a new Collector; it uses isFatal to distinguish between
+// warnings and fatal errors.
+func NewCollector(isFatal func(error) bool) *Collector {
+	return &Collector{IsFatal: isFatal}
+}
+
+// Collect collects a single error (warning or fatal). It returns nil if
+// collection can continue (only warnings so far), or otherwise the errors
+// collected. Collect mustn't be called after the first fatal error or after
+// Done has been called.
+func (c *Collector) Collect(err error) error {
+	if c.done {
+		panic("warnings.Collector already done")
+	}
+	if err == nil {
+		return nil
+	}
+	if c.IsFatal(err) {
+		c.done = true
+		c.l.Fatal = err
+	} else {
+		c.l.Warnings = append(c.l.Warnings, err)
+	}
+	if c.l.Fatal != nil {
+		return c.erorr()
+	}
+	return nil
+}
+
+// Done ends collection and returns the collected error(s).
+func (c *Collector) Done() error {
+	c.done = true
+	return c.erorr()
+}
+
+func (c *Collector) erorr() error {
+	if !c.FatalWithWarnings && c.l.Fatal != nil {
+		return c.l.Fatal
+	}
+	if c.l.Fatal == nil && len(c.l.Warnings) == 0 {
+		return nil
+	}
+	// Note that a single warning is also returned as a List. This is to make it
+	// easier to determine fatal-ness of the returned error.
+	return c.l
+}
+
+// FatalOnly returns the fatal error, if any, **in an error returned by a
+// Collector**. It returns nil if and only if err is nil or err is a List
+// with err.Fatal == nil.
+func FatalOnly(err error) error {
+	l, ok := err.(List)
+	if !ok {
+		return err
+	}
+	return l.Fatal
+}
+
+// WarningsOnly returns the warnings **in an error returned by a Collector**.
+func WarningsOnly(err error) []error {
+	l, ok := err.(List)
+	if !ok {
+		return nil
+	}
+	return l.Warnings
+}