From da3b49d9ed890b5c53d40bb88b441912a9538f00 Mon Sep 17 00:00:00 2001
From: Kyle Fuller <inbox@kylefuller.co.uk>
Date: Sat, 25 Oct 2014 13:03:58 +0100
Subject: [PATCH] Complete lexer implementation

---
 Stencil/Lexer.swift           | 44 ++++++++++++++++++++++++++++++++++-
 StencilTests/LexerTests.swift | 26 +++++++++++++++++++++
 2 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/Stencil/Lexer.swift b/Stencil/Lexer.swift
index 76819cd..133daaa 100644
--- a/Stencil/Lexer.swift
+++ b/Stencil/Lexer.swift
@@ -10,12 +10,54 @@ import Foundation
 
 public struct Lexer {
     public let templateString:String
+    let regex = NSRegularExpression(pattern: "(\\{\\{.*\\}\\}|\\{%.*%\\}|\\{#.*#\\})", options: nil, error: nil)
 
     public init(templateString:String) {
         self.templateString = templateString
     }
 
+    func createToken(string:String) -> Token {
+        func strip() -> String {
+            return string[string.startIndex.successor().successor()..<string.endIndex.predecessor().predecessor()].stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
+        }
+
+        if string.hasPrefix("{{") {
+            return Token.Variable(value: strip())
+        } else if string.hasPrefix("{%") {
+            return Token.Block(value: strip())
+        } else if string.hasPrefix("{#") {
+            return Token.Comment(value: strip())
+        }
+
+        return Token.Text(value: string)
+    }
+
     public func tokenize() -> [Token] {
-        return [Token.Text(value: templateString)]
+        // Unfortunately NSRegularExpression doesn't have a split.
+        // So here's a really terrible implementation
+
+        var tokens = [Token]()
+
+        let range = NSMakeRange(0, countElements(templateString))
+        var lastIndex = 0
+        let nsTemplateString = templateString as NSString
+        regex.enumerateMatchesInString(templateString, options: nil, range: range) { (result, flags, b) in
+            if result.range.location != lastIndex {
+                let previousMatch = nsTemplateString.substringWithRange(NSMakeRange(lastIndex, result.range.location))
+                tokens.append(self.createToken(previousMatch))
+            }
+
+            let match = nsTemplateString.substringWithRange(result.range)
+            tokens.append(self.createToken(match))
+
+            lastIndex = result.range.location + result.range.length
+        }
+
+        if lastIndex < countElements(templateString) {
+            let substring = (templateString as NSString).substringFromIndex(lastIndex)
+            tokens.append(Token.Text(value: substring))
+        }
+
+        return tokens
     }
 }
diff --git a/StencilTests/LexerTests.swift b/StencilTests/LexerTests.swift
index 3394445..dc13be7 100644
--- a/StencilTests/LexerTests.swift
+++ b/StencilTests/LexerTests.swift
@@ -20,4 +20,30 @@ class LexerTests: XCTestCase {
         XCTAssertEqual(tokens.first!, Token.Text(value: "Hello World"))
     }
 
+    func testTokenizeComment() {
+        let lexer = Lexer(templateString:"{# Comment #}")
+        let tokens = lexer.tokenize()
+
+        XCTAssertEqual(tokens.count, 1)
+        XCTAssertEqual(tokens.first!, Token.Comment(value: "Comment"))
+    }
+
+    func testTokenizeVariable() {
+        let lexer = Lexer(templateString:"{{ Variable }}")
+        let tokens = lexer.tokenize()
+
+        XCTAssertEqual(tokens.count, 1)
+        XCTAssertEqual(tokens.first!, Token.Variable(value: "Variable"))
+    }
+
+    func testTokenizeMixture() {
+        let lexer = Lexer(templateString:"My name is {{ name }}.")
+        let tokens = lexer.tokenize()
+
+        XCTAssertEqual(tokens.count, 3)
+        XCTAssertEqual(tokens[0], Token.Text(value: "My name is "))
+        XCTAssertEqual(tokens[1], Token.Variable(value: "name"))
+        XCTAssertEqual(tokens[2], Token.Text(value: "."))
+    }
+
 }