Implement :from filter

Author: christian-schilling

docs/src/reference/filters.md

@@ -137,6 +137,11 @@ commits that don't match any of the other shas.
 Produce the history that would be the result of pushing the passed branches with the
 passed filters into the upstream.
 
+### Start filtering from a specific commit **:from(<sha>:filter)**
+
+Produce a history that keeps the original history leading up to the specified commit `<sha>` unchanged,
+but applies the given `:filter` to all commits from that commit onwards.
+
 ### Prune trivial merge commits **:prune=trivial-merge**
 
 Produce a history that skips all merge commits whose tree is identical to the first parents

josh-core/src/filter/grammar.pest

@@ -24,6 +24,8 @@ filter_spec = { (
     filter_group
   | filter_message
   | filter_rev
+  | filter_from
+  | filter_concat
   | filter_join
   | filter_replace
   | filter_squash
@@ -53,6 +55,24 @@ filter_rev = {
     ~ ")"
 }
 
+filter_from = {
+    CMD_START ~ "from" ~ "("
+    ~ NEWLINE*
+    ~ (rev ~ filter_spec)?
+    ~ (CMD_SEP+ ~ (rev ~ filter_spec))*
+    ~ NEWLINE*
+    ~ ")"
+}
+
+filter_concat = {
+    CMD_START ~ "concat" ~ "("
+    ~ NEWLINE*
+    ~ (rev ~ filter_spec)?
+    ~ (CMD_SEP+ ~ (rev ~ filter_spec))*
+    ~ NEWLINE*
+    ~ ")"
+}
+
 filter_join = {
     CMD_START ~ "join" ~ "("
     ~ NEWLINE*
@@ -62,7 +82,6 @@ filter_join = {
     ~ ")"
 }
 
-
 filter_replace = {
     CMD_START ~ "replace" ~ "("
     ~ NEWLINE*

josh-core/src/filter/mod.rs

@@ -317,6 +317,8 @@ enum Op {
     Pattern(String),
     Message(String, regex::Regex),
 
+    HistoryConcat(LazyRef, Filter),
+
     Compose(Vec<Filter>),
     Chain(Filter, Filter),
     Subtract(Filter, Filter),
@@ -441,6 +443,13 @@ fn lazy_refs2(op: &Op) -> Vec<String> {
             av
         }
         Op::Rev(filters) => lazy_refs2(&Op::Join(filters.clone())),
+        Op::HistoryConcat(r, _) => {
+            let mut lr = Vec::new();
+            if let LazyRef::Lazy(s) = r {
+                lr.push(s.to_owned());
+            }
+            lr
+        }
         Op::Join(filters) => {
             let mut lr = lazy_refs2(&Op::Compose(filters.values().copied().collect()));
             lr.extend(filters.keys().filter_map(|x| {
@@ -501,6 +510,19 @@ fn resolve_refs2(refs: &std::collections::HashMap<String, git2::Oid>, op: &Op) -
                 .collect();
             Op::Rev(lr)
         }
+        Op::HistoryConcat(r, filter) => {
+            let f = resolve_refs(refs, *filter);
+            let resolved_ref = if let LazyRef::Lazy(s) = r {
+                if let Some(res) = refs.get(s) {
+                    LazyRef::Resolved(*res)
+                } else {
+                    r.clone()
+                }
+            } else {
+                r.clone()
+            };
+            Op::HistoryConcat(resolved_ref, f)
+        }
         Op::Join(filters) => {
             let lr = filters
                 .iter()
@@ -658,6 +680,9 @@ fn spec2(op: &Op) -> String {
         Op::Message(m, r) => {
             format!(":{};{}", parse::quote(m), parse::quote(r.as_str()))
         }
+        Op::HistoryConcat(r, filter) => {
+            format!(":concat({}{})", r.to_string(), spec(*filter))
+        }
         Op::Hook(hook) => {
             format!(":hook={}", parse::quote(hook))
         }
@@ -1113,6 +1138,19 @@ fn apply_to_commit2(
 
             return per_rev_filter(transaction, commit, filter, commit_filter, parent_filters);
         }
+        Op::HistoryConcat(r, f) => {
+            if let LazyRef::Resolved(c) = r {
+                let a = apply_to_commit2(&to_op(*f), &repo.find_commit(*c)?, transaction)?;
+                let a = some_or!(a, { return Ok(None) });
+                if commit.id() == a {
+                    transaction.insert(filter, commit.id(), *c, true);
+                    return Ok(Some(*c));
+                }
+            } else {
+                return Err(josh_error("unresolved lazy ref"));
+            }
+            Apply::from_commit(commit)?
+        }
         _ => apply(transaction, filter, Apply::from_commit(commit)?)?,
     };
 
@@ -1177,6 +1215,7 @@ fn apply2<'a>(transaction: &'a cache::Transaction, op: &Op, x: Apply<'a>) -> Jos
 
             Ok(x.with_message(text::transform_with_template(&r, &m, &message, &hm)?))
         }
+        Op::HistoryConcat(..) => Ok(x),
         Op::Linear => Ok(x),
         Op::Prune => Ok(x),
         Op::Unsign => Ok(x),

josh-core/src/filter/parse.rs

@@ -178,6 +178,31 @@ fn parse_item(pair: pest::iterators::Pair<Rule>) -> JoshResult<Op> {
 
             Ok(Op::Rev(hm))
         }
+        Rule::filter_from => {
+            let v: Vec<_> = pair.into_inner().map(|x| x.as_str()).collect();
+
+            if v.len() == 2 {
+                let oid = LazyRef::parse(v[0])?;
+                let filter = parse(v[1])?;
+                Ok(Op::Chain(
+                    filter,
+                    filter::to_filter(Op::HistoryConcat(oid, filter)),
+                ))
+            } else {
+                Err(josh_error("wrong argument count for :from"))
+            }
+        }
+        Rule::filter_concat => {
+            let v: Vec<_> = pair.into_inner().map(|x| x.as_str()).collect();
+
+            if v.len() == 2 {
+                let oid = LazyRef::parse(v[0])?;
+                let filter = parse(v[1])?;
+                Ok(Op::HistoryConcat(oid, filter))
+            } else {
+                Err(josh_error("wrong argument count for :concat"))
+            }
+        }
         Rule::filter_replace => {
             let replacements = pair
                 .into_inner()

josh-core/src/filter/persist.rs

@@ -290,6 +290,10 @@ impl InMemoryBuilder {
                 let params_tree = self.build_rev_params(&v)?;
                 push_tree_entries(&mut entries, [("join", params_tree)]);
             }
+            Op::HistoryConcat(lr, f) => {
+                let params_tree = self.build_rev_params(&[(lr.to_string(), *f)])?;
+                push_tree_entries(&mut entries, [("concat", params_tree)]);
+            }
             Op::Squash(Some(ids)) => {
                 let mut v = ids
                     .iter()
@@ -635,6 +639,28 @@ fn from_tree2(repo: &git2::Repository, tree_oid: git2::Oid) -> JoshResult<Op> {
             }
             Ok(Op::Join(filters))
         }
+        "concat" => {
+            let concat_tree = repo.find_tree(entry.id())?;
+            let entry = concat_tree
+                .get(0)
+                .ok_or_else(|| josh_error("concat: missing entry"))?;
+            let inner_tree = repo.find_tree(entry.id())?;
+            let key_blob = repo.find_blob(
+                inner_tree
+                    .get_name("o")
+                    .ok_or_else(|| josh_error("concat: missing key"))?
+                    .id(),
+            )?;
+            let filter_tree = repo.find_tree(
+                inner_tree
+                    .get_name("f")
+                    .ok_or_else(|| josh_error("concat: missing filter"))?
+                    .id(),
+            )?;
+            let key = std::str::from_utf8(key_blob.content())?.to_string();
+            let filter = from_tree2(repo, filter_tree.id())?;
+            Ok(Op::HistoryConcat(LazyRef::parse(&key)?, to_filter(filter)))
+        }
         "squash" => {
             // blob -> Squash(None), tree -> Squash(Some(...))
             if let Some(kind) = entry.kind() {

tests/filter/concat.t

@@ -0,0 +1,42 @@
+  $ export TESTTMP=${PWD}
+
+  $ cd ${TESTTMP}
+  $ git init -q libs 1> /dev/null
+  $ cd libs
+
+  $ mkdir sub1
+  $ echo contents1 > sub1/file1
+  $ git add sub1
+  $ git commit -m "add file1" 1> /dev/null
+
+  $ echo contents2 > sub1/file2
+  $ git add sub1
+  $ git commit -m "add file2" 1> /dev/null
+  $ git update-ref refs/heads/from_here HEAD
+
+
+  $ mkdir sub2
+  $ echo contents1 > sub2/file3
+  $ git add sub2
+  $ git commit -m "add file3" 1> /dev/null
+
+  $ josh-filter ":\"x\""
+
+  $ git log --graph --pretty=%s:%H HEAD
+  * add file3:667a912db7482f3c8023082c9b4c7b267792633a
+  * add file2:81b10fb4984d20142cd275b89c91c346e536876a
+  * add file1:bb282e9cdc1b972fffd08fd21eead43bc0c83cb8
+
+  $ git log --graph --pretty=%s:%H FILTERED_HEAD
+  * x:9d117d96dfdba145df43ebe37d9e526acac4b17c
+  * x:b232aa8eefaadfb5e38b3ad7355118aa59fb651e
+  * x:6b4d1f87c2be08f7d0f9d40b6679aab612e259b1
+
+  $ josh-filter -p ":from(81b10fb4984d20142cd275b89c91c346e536876a:\"x\")"
+  :"x":concat(81b10fb4984d20142cd275b89c91c346e536876a:"x")
+  $ josh-filter ":from(81b10fb4984d20142cd275b89c91c346e536876a:\"x\")"
+
+  $ git log --graph --pretty=%s FILTERED_HEAD
+  * x
+  * add file2
+  * add file1