Implement ":replace" filter

Allows replacement inside of files using a regular expression.

Change-Id: regex-replace

docs/src/reference/filters.md

@@ -62,6 +62,9 @@ The resulting tree will contain the contents of the
 workspace root as well as additional files specifed in the ``workspace.josh`` file.
 (see [Workspaces](./workspace.md))
 
+### Text replacement **`:replace="regex","replacement"`
+Applies the supplied regular expression to every file in the input tree.
+
 ## Pattern filters
 
 The following filters accept a glob like pattern ``X`` that can contain ``*`` to

src/filter/mod.rs

@@ -66,6 +66,8 @@ enum Op {
     Squash,
     Linear,
 
+    RegexReplace(regex::Regex, String),
+
     #[cfg(feature = "search")]
     Index,
     Invert,
@@ -190,6 +192,13 @@ fn spec2(op: &Op) -> String {
         Op::Workspace(path) => {
             format!(":workspace={}", parse::quote(&path.to_string_lossy()))
         }
+        Op::RegexReplace(regex, replacement) => {
+            format!(
+                ":replace={},{}",
+                parse::quote(&regex.to_string()),
+                parse::quote(&replacement)
+            )
+        }
 
         Op::Chain(a, b) => match (to_op(*a), to_op(*b)) {
             (Op::Subdir(p1), Op::Prefix(p2)) if p1 == p2 => {
@@ -526,6 +535,10 @@ fn apply2<'a>(
         Op::Squash => Ok(tree),
         Op::Linear => Ok(tree),
 
+        Op::RegexReplace(regex, replacement) => {
+            tree::regex_replace(tree.id(), &regex, &replacement, transaction)
+        }
+
         Op::Glob(pattern) => {
             let pattern = glob::Pattern::new(pattern)?;
             let options = glob::MatchOptions {

src/filter/opt.rs

@@ -420,6 +420,7 @@ pub fn invert(filter: Filter) -> JoshResult<Filter> {
         Op::File(path) => Some(Op::File(path)),
         Op::Prefix(path) => Some(Op::Subdir(path)),
         Op::Glob(pattern) => Some(Op::Glob(pattern)),
+        Op::RegexReplace(_, _) => Some(Op::Nop),
         _ => None,
     };
 

src/filter/parse.rs

@@ -6,6 +6,10 @@ fn make_op(args: &[&str]) -> JoshResult<Op> {
         ["nop"] => Ok(Op::Nop),
         ["empty"] => Ok(Op::Empty),
         ["prefix", arg] => Ok(Op::Prefix(Path::new(arg).to_owned())),
+        ["replace", regex, replacement] => Ok(Op::RegexReplace(
+            regex::Regex::new(regex)?,
+            replacement.to_string(),
+        )),
         ["workspace", arg] => Ok(Op::Workspace(Path::new(arg).to_owned())),
         ["prefix"] => Err(josh_error(indoc!(
             r#"

src/filter/tree.rs

@@ -57,6 +57,43 @@ pub fn pathstree<'a>(
     Ok(result)
 }
 
+pub fn regex_replace<'a>(
+    input: git2::Oid,
+    regex: &regex::Regex,
+    replacement: &str,
+    transaction: &'a cache::Transaction,
+) -> super::JoshResult<git2::Tree<'a>> {
+    let repo = transaction.repo();
+
+    let tree = repo.find_tree(input)?;
+    let mut result = tree::empty(repo);
+
+    for entry in tree.iter() {
+        let name = entry.name().ok_or(super::josh_error("no name"))?;
+        if entry.kind() == Some(git2::ObjectType::Blob) {
+            let file_contents = get_blob(repo, &tree, std::path::Path::new(&name));
+            let replaced = regex.replacen(&file_contents, 0, replacement);
+
+            result = replace_child(
+                repo,
+                std::path::Path::new(name),
+                repo.blob(replaced.as_bytes())?,
+                entry.filemode(),
+                &result,
+            )?;
+        }
+
+        if entry.kind() == Some(git2::ObjectType::Tree) {
+            let s = regex_replace(entry.id(), regex, replacement, transaction)?.id();
+
+            if s != tree::empty_id() {
+                result = replace_child(repo, std::path::Path::new(name), s, 0o0040000, &result)?;
+            }
+        }
+    }
+    Ok(result)
+}
+
 pub fn remove_pred<'a>(
     transaction: &'a cache::Transaction,
     root: &str,

tests/filter/replace.t

@@ -0,0 +1,53 @@
+
+  $ export TESTTMP=${PWD}
+
+  $ cd ${TESTTMP}
+  $ git init -q repo 1>/dev/null
+  $ cd repo
+
+  $ echo "hello world" > hw.txt
+  $ mkdir subdir
+  $ echo "hello moon" > subdir/hw.txt
+
+  $ git add .
+  $ git commit -m initial
+  [master (root-commit) 79f224d] initial
+   2 files changed, 2 insertions(+)
+   create mode 100644 hw.txt
+   create mode 100644 subdir/hw.txt
+
+  $ git diff ${EMPTY_TREE}..HEAD
+  diff --git a/hw.txt b/hw.txt
+  new file mode 100644
+  index 0000000..3b18e51
+  --- /dev/null
+  +++ b/hw.txt
+  @@ -0,0 +1 @@
+  +hello world
+  diff --git a/subdir/hw.txt b/subdir/hw.txt
+  new file mode 100644
+  index 0000000..1b95c6e
+  --- /dev/null
+  +++ b/subdir/hw.txt
+  @@ -0,0 +1 @@
+  +hello moon
+
+  $ josh-filter -p ':replace="hello","bye":replace="^(?P<l>.*(?m))$","$l!"'
+  :replace=hello,bye:replace="^(?P<l>.*(?m))$","$l!"
+  $ josh-filter ':replace="hello","bye":replace="(?m)^(?P<l>.+)$","$l!"'
+
+  $ git diff ${EMPTY_TREE}..FILTERED_HEAD
+  diff --git a/hw.txt b/hw.txt
+  new file mode 100644
+  index 0000000..9836695
+  --- /dev/null
+  +++ b/hw.txt
+  @@ -0,0 +1 @@
+  +bye world!
+  diff --git a/subdir/hw.txt b/subdir/hw.txt
+  new file mode 100644
+  index 0000000..cb72486
+  --- /dev/null
+  +++ b/subdir/hw.txt
+  @@ -0,0 +1 @@
+  +bye moon!