emote: add emote parsing engine

emote/emote.go

@@ -0,0 +1,65 @@
+package emote
+
+import (
+	"strings"
+	"unicode"
+)
+
+// Emote is the information Kaiyan needs about an emote.
+type Emote struct {
+	// ID is the emote ID per the source.
+	ID string
+	// Name is the text of the emote as would be parsed from message text.
+	Name string
+	// Source is the name of the emote source, e.g. "7TV", "Twitch:cirno_tv", &c.
+	Source string
+	// Link is a hyperlink to manage the emote.
+	Link string
+	// Image is a hyperlink to the emote image of any size.
+	Image string
+}
+
+// Parser finds emotes in a message.
+//
+// Parser assumes that emotes are bound by whitespace.
+type Parser struct {
+	m map[string]string
+	// TODO(branden): more efficient data structure; trie?
+}
+
+// NewParser creates a Parser for the given list of emotes.
+func NewParser(emotes ...Emote) Parser {
+	m := make(map[string]string, len(emotes))
+	for _, e := range emotes {
+		m[e.Name] = e.ID
+	}
+	return Parser{m}
+}
+
+// Next parses the next emote instance from the message and returns the
+// remainder of the message text following it.
+// If there is no emote in the message the returned emote is the empty string.
+func (p Parser) Next(text string) (name, id, following string) {
+	for text != "" {
+		// First trim any existing space.
+		text = strings.TrimSpace(text)
+		// Then look for the next space.
+		// If there is none, this is the last word of the message; we still
+		// need to look it up.
+		k := strings.IndexFunc(text, unicode.IsSpace)
+		word := text
+		if k >= 0 {
+			word = text[:k]
+			following = text[k:]
+		} else {
+			following = ""
+		}
+		id = p.m[word]
+		if id != "" {
+			return word, id, following
+		}
+		text = following
+	}
+	// No emote found.
+	return "", "", ""
+}