From 6785bade8f9a9636fc468223e33b9c12002ac593 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin@jemstep.com>
Date: Mon, 30 Mar 2020 10:50:06 +0200
Subject: Added a lazily-executed variant of policy result chaining

---
 src/policies.rs               | 42 ++++++++++++++++++++----------------------
 src/policies/policy_result.rs | 10 ++++++++++
 2 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/src/policies.rs b/src/policies.rs
index 5eed65f..fb10aed 100644
--- a/src/policies.rs
+++ b/src/policies.rs
@@ -70,37 +70,35 @@ pub fn verify_git_commits<G: Git, P: Gpg>(
         )?;
 
         if config.verify_email_addresses {
-            policy_result = policy_result.and(verify_email_addresses(
-                &config.author_domain,
-                &config.committer_domain,
-                &not_manually_verified_commits,
-            ));
+            policy_result = policy_result.and_then(|| {
+                Ok(verify_email_addresses(
+                    &config.author_domain,
+                    &config.committer_domain,
+                    &not_manually_verified_commits,
+                ))
+            })?;
         }
 
         if config.verify_commit_signatures {
-            policy_result = policy_result.and(verify_commit_signatures::<G, P>(
-                git,
-                &gpg,
-                &not_manually_verified_commits,
-                &mut keyring,
-            )?);
+            policy_result = policy_result.and_then(|| {
+                verify_commit_signatures::<G, P>(
+                    git,
+                    &gpg,
+                    &not_manually_verified_commits,
+                    &mut keyring,
+                )
+            })?;
         }
 
         if config.verify_different_authors {
-            policy_result = policy_result.and(verify_different_authors::<G>(
-                &all_commits,
-                git,
-                &ref_update,
-            )?);
+            policy_result = policy_result
+                .and_then(|| verify_different_authors::<G>(&all_commits, git, &ref_update))?;
         }
 
         if config.verify_rebased {
-            policy_result = policy_result.and(verify_rebased::<G>(
-                &all_commits,
-                git,
-                &ref_update,
-                &config.override_tag_pattern,
-            )?);
+            policy_result = policy_result.and_then(|| {
+                verify_rebased::<G>(&all_commits, git, &ref_update, &config.override_tag_pattern)
+            })?;
         }
     }
 
diff --git a/src/policies/policy_result.rs b/src/policies/policy_result.rs
index e12ff42..852c705 100644
--- a/src/policies/policy_result.rs
+++ b/src/policies/policy_result.rs
@@ -1,4 +1,5 @@
 use git2::Oid;
+use std::error::Error;
 use std::fmt;
 use std::iter;
 
@@ -22,6 +23,15 @@ impl PolicyResult {
             x => x,
         }
     }
+    pub fn and_then(
+        self,
+        mut next: impl FnMut() -> Result<PolicyResult, Box<dyn Error>>,
+    ) -> Result<PolicyResult, Box<dyn Error>> {
+        match self {
+            PolicyResult::Ok => next(),
+            x => Ok(x),
+        }
+    }
     pub fn is_ok(&self) -> bool {
         match self {
             PolicyResult::Ok => true,
-- 
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