Re-wrote from scratch in Golang

- Re-implemented the project in Golang, and deprecated Python entirely
- Implemented several new, long-requested features
- Refactored cheatsheets into a separate repository

internal/sheet/search.go

@@ -0,0 +1,45 @@
+package sheet
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/mgutz/ansi"
+)
+
+// Search searches for regexp matches in a cheatsheet's text, and optionally
+// colorizes matching strings.
+func (s *Sheet) Search(reg *regexp.Regexp, colorize bool) []Match {
+
+	// record matches
+	matches := []Match{}
+
+	// search through the cheatsheet's text line by line
+	// TODO: searching line-by-line is surely the "naive" approach. Revisit this
+	// later with an eye for performance improvements.
+	for linenum, line := range strings.Split(s.Text, "\n") {
+
+		// exit early if the line doesn't match the regex
+		if !reg.MatchString(line) {
+			continue
+		}
+
+		// init the match
+		m := Match{
+			Line: linenum + 1,
+			Text: strings.TrimSpace(line),
+		}
+
+		// colorize the matching text if so configured
+		if colorize {
+			m.Text = reg.ReplaceAllStringFunc(m.Text, func(matched string) string {
+				return ansi.Color(matched, "red+b")
+			})
+		}
+
+		// record the match
+		matches = append(matches, m)
+	}
+
+	return matches
+}