Add search feature using grep.

src/lib.rs

@@ -10,6 +10,7 @@ extern crate git2;
 extern crate regex;
 extern crate pathdiff;
 extern crate chrono;
+extern crate grep;
 #[macro_use] extern crate toml;
 
 use std::fs;
@@ -724,3 +725,55 @@ impl<'a> Linker<'a> {
         }
     }
 }
+
+pub struct Searcher<'a> {
+    historian: &'a Historian
+}
+
+#[derive(Serialize)]
+pub struct SearchResult {
+    pub page: Page,
+    pub matches: Vec<String>
+}
+
+impl<'a> Searcher<'a> {
+    pub fn new(historian: &Historian) -> Searcher {
+        Searcher {
+            historian
+        }
+    }
+
+    pub fn search(&self, root: &Page, query: &str) -> Vec<SearchResult> {
+        let mut searcher = grep::searcher::SearcherBuilder::new().build();
+        let matcher = grep::regex::RegexMatcherBuilder::new()
+            .fixed_strings(true)
+            .case_insensitive(true)
+            .build(query)
+            .unwrap();
+
+        let mut results: Vec<SearchResult> = vec![];
+        self.do_search(root, &mut results, &mut searcher, &matcher);
+        results
+    }
+
+    fn do_search(&self, root: &Page, results: &mut Vec<SearchResult>, searcher: &mut grep::searcher::Searcher, matcher: &grep::regex::RegexMatcher) {
+        for child in &root.children {
+            if let Some(child_page) = self.historian.resolve_to_page(&child.full_name) {
+                let mut matches: Vec<String> = vec![];
+                searcher.search_path(matcher, &child.path, grep::searcher::sinks::UTF8(|lnum, line| {
+                    matches.push(line.to_owned());
+                    Ok(true)
+                }));
+                
+                self.do_search(&child_page, results, searcher, matcher);
+
+                if !matches.is_empty() {
+                    results.push(SearchResult {
+                        page: child_page,
+                        matches
+                    });
+                }
+            }
+        }
+    }
+}