printer: add --passthru flag

The --passthru flag causes ripgrep to print every line,
even if the line does not contain a match. This is a
response to the common pattern of `^|foo` to match every
line, while still highlighting things like `foo`.

Fixes #740 

6 files changed, 84 insertions, 5 deletions

diff --git a/complete/_rg b/complete/_rg
index 93ab4ae8..8455c804 100644
--- a/complete/_rg
+++ b/complete/_rg
@@ -26,7 +26,7 @@ _rg() {
     '--column[show column numbers]'
     '(-A -B -C --after-context --before-context --context)'{-C+,--context=}'[specify lines to show before and after each match]:number of lines'
     '--context-separator=[specify string used to separate non-continuous context lines in output]:separator'
-    '(-c --count)'{-c,--count}'[only show count of matches for each file]'
+    '(-c --count --passthrough --passthru)'{-c,--count}'[only show count of matches for each file]'
     '--debug[show debug messages]'
     '--dfa-size-limit=[specify upper size limit of generated DFA]:DFA size'
     '(-E --encoding)'{-E+,--encoding=}'[specify text encoding of files to search]: :_rg_encodings'
@@ -61,13 +61,15 @@ _rg() {
     '--no-messages[suppress all error messages]'
     "(--mmap --no-mmap)--no-mmap[don't search using memory maps]"
     '(-0 --null)'{-0,--null}'[print NUL byte after file names]'
-    '(-o --only-matching -r --replace)'{-o,--only-matching}'[show only matching part of each line]'
+    '(-o -r --only-matching --passthrough --passthru --replace)'{-o,--only-matching}'[show only matching part of each line]'
+    '(-c -o -r --count --only-matching --passthrough --replace)--passthru[show both matching and non-matching lines]'
+    '!(-c -o -r --count --only-matching --passthru --replace)--passthrough'
     '--path-separator=[specify path separator to use when printing file names]:separator'
     '(-p --heading --no-heading --pretty --vimgrep)'{-p,--pretty}'[alias for --color=always --heading -n]'
     '(-q --quiet)'{-q,--quiet}'[suppress normal output]'
     '--regex-size-limit=[specify upper size limit of compiled regex]:regex size'
     '(1 -f --file)*'{-e+,--regexp=}'[specify pattern]:pattern'
-    '(-o --only-matching -r --replace)'{-r+,--replace=}'[specify string used to replace matches]:replace string'
+    '(-c -o -r --count --only-matching --passthrough --passthru --replace)'{-r+,--replace=}'[specify string used to replace matches]:replace string'
     '(-i -s -S --ignore-case --case-sensitive --smart-case)'{-S,--smart-case}'[search case-insensitively if the pattern is all lowercase]'
     '(-j --threads)--sort-files[sort results by file path (disables parallelism)]'
     '(-a --text)'{-a,--text}'[search binary files as if they were text]'
diff --git a/doc/rg.1 b/doc/rg.1
index c098410b..d8272e74 100644
--- a/doc/rg.1
+++ b/doc/rg.1
@@ -435,6 +435,14 @@ such part on a separate output line.
 .RS
 .RE
 .TP
+.B \-\-passthru, \-\-passthrough
+Show both matching and non\-matching lines.
+This is equivalent to adding ^ to the list of search patterns.
+This option overrides \-\-count and cannot be used with
+\-\-only\-matching or \-\-replace.
+.RS
+.RE
+.TP
 .B \-\-path\-separator \f[I]SEPARATOR\f[]
 The path separator to use when printing file paths.
 This defaults to your platform\[aq]s path separator, which is / on Unix
diff --git a/doc/rg.1.md b/doc/rg.1.md
index 2cd7059e..93b401ab 100644
--- a/doc/rg.1.md
+++ b/doc/rg.1.md
@@ -288,6 +288,10 @@ Project home page: https://github.com/BurntSushi/ripgrep
 : Print only the matched (non-empty) parts of a matching line, with each such
   part on a separate output line.
 
+--passthru, --passthrough
+: Show both matching and non-matching lines. This option cannot be used with
+  --only-matching or --replace.
+
 --path-separator *SEPARATOR*
 : The path separator to use when printing file paths. This defaults to your
   platform's path separator, which is / on Unix and \\ on Windows. This flag is
diff --git a/src/app.rs b/src/app.rs
index bcc91f8c..6bf2744e 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -166,6 +166,8 @@ pub fn app() -> App<'static, 'static> {
         .arg(flag("no-ignore-vcs"))
         .arg(flag("null").short("0"))
         .arg(flag("only-matching").short("o"))
+        .arg(flag("passthru").alias("passthrough")
+            .conflicts_with_all(&["only-matching", "replace"]))
         .arg(flag("path-separator").value_name("SEPARATOR").takes_value(true))
         .arg(flag("pretty").short("p"))
         .arg(flag("replace").short("r")
@@ -499,6 +501,8 @@ lazy_static! {
              "Print only matched parts of a line.",
              "Print only the matched (non-empty) parts of a matching line, \
               with each such part on a separate output line.");
+        doc!(h, "passthru",
+             "Show both matching and non-matching lines.");
         doc!(h, "path-separator",
              "Path separator to use when printing file paths.",
              "The path separator to use when printing file paths. This \
diff --git a/src/args.rs b/src/args.rs
index 6affa2dd..d2d0232b 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -433,7 +433,9 @@ impl<'a> ArgMatches<'a> {
     /// Note that if -F/--fixed-strings is set, then all patterns will be
     /// escaped. Similarly, if -w/--word-regexp is set, then all patterns
     /// are surrounded by `\b`, and if -x/--line-regexp is set, then all
-    /// patterns are surrounded by `^...$`.
+    /// patterns are surrounded by `^...$`. Finally, if --passthru is set,
+    /// the pattern `^` is added to the end (to ensure that it works as
+    /// expected with multiple -e/-f patterns).
     ///
     /// If any pattern is invalid UTF-8, then an error is returned.
     fn patterns(&self) -> Result<Vec<String>> {
@@ -470,7 +472,11 @@ impl<'a> ArgMatches<'a> {
                 }
             }
         }
-        if pats.is_empty() {
+        // It's important that this be at the end; otherwise it would always
+        // match first, and we wouldn't get colours in the output
+        if self.is_present("passthru") && !self.is_present("count") {
+            pats.push("^".to_string())
+        } else if pats.is_empty() {
             pats.push(self.empty_pattern())
         }
         Ok(pats)
diff --git a/tests/tests.rs b/tests/tests.rs
index 4bd852cd..646b02fa 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -1610,6 +1610,61 @@ clean!(suggest_fixed_strings_for_invalid_regex, "foo(", ".",
 });
 
 #[test]
+fn feature_740_passthru() {
+    let wd = WorkDir::new("feature_740");
+    wd.create("file", "\nfoo\nbar\nfoobar\n\nbaz\n");
+    wd.create("patterns", "foo\n\nbar\n");
+
+    // We can't assume that the way colour specs are translated to ANSI
+    // sequences will remain stable, and --replace doesn't currently work with
+    // pass-through, so for now we don't actually test the match sub-strings
+    let common_args = &["-n", "--passthru"];
+    let expected = "\
+1:
+2:foo
+3:bar
+4:foobar
+5:
+6:baz
+";
+
+    // With single pattern
+    let mut cmd = wd.command();
+    cmd.args(common_args).arg("foo").arg("file");
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, expected);
+
+    // With multiple -e patterns
+    let mut cmd = wd.command();
+    cmd.args(common_args)
+        .arg("-e").arg("foo").arg("-e").arg("bar").arg("file");
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, expected);
+
+    // With multiple -f patterns
+    let mut cmd = wd.command();
+    cmd.args(common_args).arg("-f").arg("patterns").arg("file");
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, expected);
+
+    // -c should override
+    let mut cmd = wd.command();
+    cmd.args(common_args).arg("-c").arg("foo").arg("file");
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, "2\n");
+
+    // -o should conflict
+    let mut cmd = wd.command();
+    cmd.args(common_args).arg("-o").arg("foo").arg("file");
+    wd.assert_err(&mut cmd);
+
+    // -r should conflict
+    let mut cmd = wd.command();
+    cmd.args(common_args).arg("-r").arg("$0").arg("foo").arg("file");
+    wd.assert_err(&mut cmd);
+}
+
+#[test]
 fn binary_nosearch() {
     let wd = WorkDir::new("binary_nosearch");
     wd.create("file", "foo\x00bar\nfoo\x00baz\n");