added a condition section to YAML elements

plugin/condition/condition.go

@@ -0,0 +1,53 @@
+package condition
+
+type Condition struct {
+	Owner       string // Indicates the step should run only for this repo (useful for forks)
+	Branch      string // Indicates the step should run only for this branch
+	Condition   string // Indicates the step should run if bash condition evals to true
+	PullRequest *bool  `yaml:"pull_requests"` // Indicates the step should run for all pull requests
+	AllBranches *bool  `yaml:"all_branches"`  // Indicates the step should run for all branches
+
+	// Indicates the step should only run when the following
+	// matrix values are present for the sub-build.
+	Matrix map[string]string
+}
+
+// MatchPullRequest is a helper function that returns false
+// if Pull Requests are disbled, but the pull request string
+// is not empty.
+func (c *Condition) MatchPullRequest(pr string) bool {
+	if len(pr) == 0 {
+		return true
+	}
+	if c.PullRequest == nil {
+		return false
+	}
+	return *c.PullRequest
+}
+
+// MatchBranch is a helper function that returns true
+// if all_branches is true. Else it returns false if a
+// branch condition is specified, and the branch does
+// not match.
+func (c *Condition) MatchBranch(branch string) bool {
+	if len(c.Branch) == 0 {
+		return true
+	}
+	if c.AllBranches != nil && *c.AllBranches == true {
+		return true
+	}
+	return c.Branch == branch
+}
+
+// MatchOwner is a helper function that returns false
+// if an owner condition is specified and the repository
+// owner does not match.
+//
+// This is useful when you want to prevent forks from
+// executing deployment, publish or notification steps.
+func (c *Condition) MatchOwner(owner string) bool {
+	if len(c.Owner) == 0 {
+		return true
+	}
+	return c.Owner == owner
+}