Merge pull request #1100 from carolynvs/standarized-importer-pattern

Standardize the importers

cmd/dep/base_importer.go

@@ -0,0 +1,277 @@
+// Copyright 2017 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 main
+
+import (
+	"log"
+
+	"github.com/golang/dep"
+	fb "github.com/golang/dep/internal/feedback"
+	"github.com/golang/dep/internal/gps"
+	"github.com/pkg/errors"
+)
+
+// baseImporter provides a common implementation for importing from other
+// dependency managers.
+type baseImporter struct {
+	logger   *log.Logger
+	verbose  bool
+	sm       gps.SourceManager
+	manifest *dep.Manifest
+	lock     *dep.Lock
+}
+
+// newBaseImporter creates a new baseImporter for embedding in an importer.
+func newBaseImporter(logger *log.Logger, verbose bool, sm gps.SourceManager) *baseImporter {
+	return &baseImporter{
+		logger:   logger,
+		verbose:  verbose,
+		manifest: dep.NewManifest(),
+		lock:     &dep.Lock{},
+		sm:       sm,
+	}
+}
+
+// isTag determines if the specified value is a tag (plain or semver).
+func (i *baseImporter) isTag(pi gps.ProjectIdentifier, value string) (bool, gps.Version, error) {
+	versions, err := i.sm.ListVersions(pi)
+	if err != nil {
+		return false, nil, errors.Wrapf(err, "unable to list versions for %s(%s)", pi.ProjectRoot, pi.Source)
+	}
+
+	for _, version := range versions {
+		if version.Type() != gps.IsVersion && version.Type() != gps.IsSemver {
+			continue
+		}
+
+		if value == version.String() {
+			return true, version, nil
+		}
+	}
+
+	return false, nil, nil
+}
+
+// lookupVersionForLockedProject figures out the appropriate version for a locked
+// project based on the locked revision and the constraint from the manifest.
+// First try matching the revision to a version, then try the constraint from the
+// manifest, then finally the revision.
+func (i *baseImporter) lookupVersionForLockedProject(pi gps.ProjectIdentifier, c gps.Constraint, rev gps.Revision) (gps.Version, error) {
+	// Find the version that goes with this revision, if any
+	versions, err := i.sm.ListVersions(pi)
+	if err != nil {
+		return rev, errors.Wrapf(err, "Unable to lookup the version represented by %s in %s(%s). Falling back to locking the revision only.", rev, pi.ProjectRoot, pi.Source)
+	}
+
+	var branchConstraint gps.PairedVersion
+	gps.SortPairedForUpgrade(versions) // Sort versions in asc order
+	matches := []gps.Version{}
+	for _, v := range versions {
+		if v.Revision() == rev {
+			matches = append(matches, v)
+		}
+		if c != nil && v.Type() == gps.IsBranch && v.String() == c.String() {
+			branchConstraint = v
+		}
+	}
+
+	// Try to narrow down the matches with the constraint. Otherwise return the first match.
+	if len(matches) > 0 {
+		if c != nil {
+			for _, v := range matches {
+				if i.testConstraint(c, v) {
+					return v, nil
+				}
+			}
+		}
+		return matches[0], nil
+	}
+
+	// Use branch constraint from the manifest
+	if branchConstraint != nil {
+		return branchConstraint.Unpair().Pair(rev), nil
+	}
+
+	// Give up and lock only to a revision
+	return rev, nil
+}
+
+// importedPackage is a common intermediate representation of a package imported
+// from an external tool's configuration.
+type importedPackage struct {
+	// Required. The package path, not necessarily the project root.
+	Name string
+
+	// Required. Text representing a revision or tag.
+	LockHint string
+
+	// Optional. Alternative source, or fork, for the project.
+	Source string
+
+	// Optional. Text representing a branch or version.
+	ConstraintHint string
+}
+
+// importedProject is a consolidated representation of a set of imported packages
+// for the same project root.
+type importedProject struct {
+	Root gps.ProjectRoot
+	importedPackage
+}
+
+// loadPackages consolidates all package references into a set of project roots.
+func (i *baseImporter) loadPackages(packages []importedPackage) ([]importedProject, error) {
+	// preserve the original order of the packages so that messages that
+	// are printed as they are processed are in a consistent order.
+	orderedProjects := make([]importedProject, 0, len(packages))
+
+	projects := make(map[gps.ProjectRoot]*importedProject, len(packages))
+	for _, pkg := range packages {
+		pr, err := i.sm.DeduceProjectRoot(pkg.Name)
+		if err != nil {
+			return nil, errors.Wrapf(err, "Cannot determine the project root for %s", pkg.Name)
+		}
+		pkg.Name = string(pr)
+
+		prj, exists := projects[pr]
+		if !exists {
+			prj := importedProject{pr, pkg}
+			orderedProjects = append(orderedProjects, prj)
+			projects[pr] = &orderedProjects[len(orderedProjects)-1]
+			continue
+		}
+
+		// The config found first "wins", though we allow for incrementally
+		// setting each field because some importers have a config and lock file.
+		if prj.Source == "" && pkg.Source != "" {
+			prj.Source = pkg.Source
+		}
+
+		if prj.ConstraintHint == "" && pkg.ConstraintHint != "" {
+			prj.ConstraintHint = pkg.ConstraintHint
+		}
+
+		if prj.LockHint == "" && pkg.LockHint != "" {
+			prj.LockHint = pkg.LockHint
+		}
+	}
+
+	return orderedProjects, nil
+}
+
+// importPackages loads imported packages into the manifest and lock.
+// - defaultConstraintFromLock specifies if a constraint should be defaulted
+//   based on the locked version when there wasn't a constraint hint.
+//
+// Rules:
+// * When a constraint is ignored, default to *.
+// * HEAD revisions default to the matching branch.
+// * Semantic versions default to ^VERSION.
+// * Revision constraints are ignored.
+// * Versions that don't satisfy the constraint, drop the constraint.
+// * Untagged revisions ignore non-branch constraint hints.
+func (i *baseImporter) importPackages(packages []importedPackage, defaultConstraintFromLock bool) (err error) {
+	projects, err := i.loadPackages(packages)
+	if err != nil {
+		return err
+	}
+
+	for _, prj := range projects {
+		pc := gps.ProjectConstraint{
+			Ident: gps.ProjectIdentifier{
+				ProjectRoot: prj.Root,
+				Source:      prj.Source,
+			},
+		}
+
+		pc.Constraint, err = i.sm.InferConstraint(prj.ConstraintHint, pc.Ident)
+		if err != nil {
+			pc.Constraint = gps.Any()
+		}
+
+		var version gps.Version
+		if prj.LockHint != "" {
+			var isTag bool
+			// Determine if the lock hint is a revision or tag
+			isTag, version, err = i.isTag(pc.Ident, prj.LockHint)
+			if err != nil {
+				return err
+			}
+
+			// If the hint is a revision, check if it is tagged
+			if !isTag {
+				revision := gps.Revision(prj.LockHint)
+				version, err = i.lookupVersionForLockedProject(pc.Ident, pc.Constraint, revision)
+				if err != nil {
+					version = nil
+					i.logger.Println(err)
+				}
+			}
+
+			// Default the constraint based on the locked version
+			if defaultConstraintFromLock && prj.ConstraintHint == "" && version != nil {
+				props := getProjectPropertiesFromVersion(version)
+				if props.Constraint != nil {
+					pc.Constraint = props.Constraint
+				}
+			}
+		}
+
+		// Ignore pinned constraints
+		if i.isConstraintPinned(pc.Constraint) {
+			if i.verbose {
+				i.logger.Printf("  Ignoring pinned constraint %v for %v.\n", pc.Constraint, pc.Ident)
+			}
+			pc.Constraint = gps.Any()
+		}
+
+		// Ignore constraints which conflict with the locked revision, so that
+		// solve doesn't later change the revision to satisfy the constraint.
+		if !i.testConstraint(pc.Constraint, version) {
+			if i.verbose {
+				i.logger.Printf("  Ignoring constraint %v for %v because it would invalidate the locked version %v.\n", pc.Constraint, pc.Ident, version)
+			}
+			pc.Constraint = gps.Any()
+		}
+
+		i.manifest.Constraints[pc.Ident.ProjectRoot] = gps.ProjectProperties{
+			Source:     pc.Ident.Source,
+			Constraint: pc.Constraint,
+		}
+		fb.NewConstraintFeedback(pc, fb.DepTypeImported).LogFeedback(i.logger)
+
+		if version != nil {
+			lp := gps.NewLockedProject(pc.Ident, version, nil)
+			i.lock.P = append(i.lock.P, lp)
+			fb.NewLockedProjectFeedback(lp, fb.DepTypeImported).LogFeedback(i.logger)
+		}
+	}
+
+	return nil
+}
+
+// isConstraintPinned returns if a constraint is pinned to a specific revision.
+func (i *baseImporter) isConstraintPinned(c gps.Constraint) bool {
+	if version, isVersion := c.(gps.Version); isVersion {
+		switch version.Type() {
+		case gps.IsRevision, gps.IsVersion:
+			return true
+		}
+	}
+	return false
+}
+
+// testConstraint verifies that the constraint won't invalidate the locked version.
+func (i *baseImporter) testConstraint(c gps.Constraint, v gps.Version) bool {
+	// Assume branch constraints are satisfied
+	if version, isVersion := c.(gps.Version); isVersion {
+		if version.Type() == gps.IsBranch {
+
+			return true
+		}
+	}
+
+	return c.Matches(v)
+}