process template lines when Lexer is created not when parsing each token. (#230)

Sources/Errors.swift

@@ -66,11 +66,11 @@ open class SimpleErrorReporter: ErrorReporter {
 
     func describe(token: Token) -> String {
       let templateName = token.sourceMap.filename ?? ""
-      let line = token.sourceMap.line
-      let highlight = "\(String(Array(repeating: " ", count: line.offset)))^\(String(Array(repeating: "~", count: max(token.contents.characters.count - 1, 0))))"
+      let location = token.sourceMap.location
+      let highlight = "\(String(Array(repeating: " ", count: location.lineOffset)))^\(String(Array(repeating: "~", count: max(token.contents.characters.count - 1, 0))))"
 
-      return "\(templateName)\(line.number):\(line.offset): error: \(templateError.reason)\n"
-        + "\(line.content)\n"
+      return "\(templateName)\(location.lineNumber):\(location.lineOffset): error: \(templateError.reason)\n"
+        + "\(location.content)\n"
         + "\(highlight)\n"
     }
 

Sources/Lexer.swift

@@ -1,12 +1,20 @@
 import Foundation
 
+typealias Line = (content: String, number: UInt, range: Range<String.Index>)
+
 struct Lexer {
   let templateName: String?
   let templateString: String
+  let lines: [Line]
 
   init(templateName: String? = nil, templateString: String) {
     self.templateName = templateName
     self.templateString = templateString
+
+    self.lines = templateString.components(separatedBy: .newlines).enumerated().flatMap {
+      guard !$0.element.isEmpty else { return nil }
+      return (content: $0.element, number: UInt($0.offset + 1), templateString.range(of: $0.element)!)
+    }
   }
 
   func createToken(string: String, at range: Range<String.Index>) -> Token {
@@ -25,8 +33,8 @@ struct Lexer {
     if string.hasPrefix("{{") || string.hasPrefix("{%") || string.hasPrefix("{#") {
       let value = strip()
       let range = templateString.range(of: value, range: range) ?? range
-      let line = templateString.rangeLine(range)
-      let sourceMap = SourceMap(filename: templateName, line: line)
+      let location = rangeLocation(range)
+      let sourceMap = SourceMap(filename: templateName, location: location)
 
       if string.hasPrefix("{{") {
         return .variable(value: value, at: sourceMap)
@@ -37,8 +45,8 @@ struct Lexer {
       }
     }
 
-    let line = templateString.rangeLine(range)
-    let sourceMap = SourceMap(filename: templateName, line: line)
+    let location = rangeLocation(range)
+    let sourceMap = SourceMap(filename: templateName, location: location)
     return .text(value: string, at: sourceMap)
   }
 
@@ -72,6 +80,14 @@ struct Lexer {
     return tokens
   }
 
+  func rangeLocation(_ range: Range<String.Index>) -> ContentLocation {
+    guard let line = self.lines.first(where: { $0.range.contains(range.lowerBound) }) else {
+      return ("", 0, 0)
+    }
+    let offset = templateString.distance(from: line.range.lowerBound, to: range.lowerBound)
+    return (line.content, line.number, offset)
+  }
+
 }
 
 class Scanner {
@@ -179,23 +195,6 @@ extension String {
     let last = findLastNot(character: character) ?? endIndex
     return String(self[first..<last])
   }
-
-  public func rangeLine(_ range: Range<String.Index>) -> RangeLine {
-    var lineNumber: UInt = 0
-    var offset: Int = 0
-    var lineContent = ""
-
-    for line in components(separatedBy: CharacterSet.newlines) {
-      lineNumber += 1
-      lineContent = line
-      if let rangeOfLine = self.range(of: line), rangeOfLine.contains(range.lowerBound) {
-        offset = distance(from: rangeOfLine.lowerBound, to: range.lowerBound)
-        break
-      }
-    }
-
-    return (lineContent, lineNumber, offset)
-  }
 }
 
-public typealias RangeLine = (content: String, number: UInt, offset: Int)
+public typealias ContentLocation = (content: String, lineNumber: UInt, lineOffset: Int)

Sources/Parser.swift

@@ -125,9 +125,9 @@ public class TokenParser {
       }
       // find offset of filter in the containing token so that only filter is highligted, not the whole token
       if let filterTokenRange = containingToken.contents.range(of: filterToken) {
-        var rangeLine = containingToken.sourceMap.line
-        rangeLine.offset += containingToken.contents.distance(from: containingToken.contents.startIndex, to: filterTokenRange.lowerBound)
-        syntaxError.token = .variable(value: filterToken, at: SourceMap(filename: containingToken.sourceMap.filename, line: rangeLine))
+        var location = containingToken.sourceMap.location
+        location.lineOffset += containingToken.contents.distance(from: containingToken.contents.startIndex, to: filterTokenRange.lowerBound)
+        syntaxError.token = .variable(value: filterToken, at: SourceMap(filename: containingToken.sourceMap.filename, location: location))
       } else {
         syntaxError.token = containingToken
       }

Sources/Tokenizer.swift

@@ -57,17 +57,17 @@ extension String {
 
 public struct SourceMap: Equatable {
   public let filename: String?
-  public let line: RangeLine
+  public let location: ContentLocation
 
-  init(filename: String? = nil, line: RangeLine = ("", 0, 0)) {
+  init(filename: String? = nil, location: ContentLocation = ("", 0, 0)) {
     self.filename = filename
-    self.line = line
+    self.location = location
   }
 
   static let unknown = SourceMap()
 
   public static func ==(lhs: SourceMap, rhs: SourceMap) -> Bool {
-    return lhs.filename == rhs.filename && lhs.line == rhs.line
+    return lhs.filename == rhs.filename && lhs.location == rhs.location
   }
 }