Initial implementation

1 files changed, 50 insertions, 0 deletions

diff --git a/Sources/WmapParser/DependencyParser.swift b/Sources/WmapParser/DependencyParser.swift
new file mode 100644
index 0000000..9964d5a
--- /dev/null
+++ b/Sources/WmapParser/DependencyParser.swift
@@ -0,0 +1,50 @@
+/// Looks for -- or ->. If found, returns where this arrow starts.
+@inline(__always)
+func hasDependency<T: Collection>(_ bytes: T, _ start: Int, _ end: Int) -> Int?
+where T.Element == UInt8, T.Index == Int {
+  var index = start
+  while index < end {
+    if bytes[index] == kOpenParenthesis { return nil }
+    if bytes[index] == kDash && index + 1 < end {
+      let next = bytes[index + 1]
+      if next == kGreaterThan || next == kDash { return index }
+    }
+    index += 1
+  }
+  return nil
+}
+
+/// Finds a dependency and whether it's directed. It assumes we previously
+/// checked for the location of our separator to speed things up.
+func parseDependency<T: Collection>(_ bytes: T, _ start: Int, _ end: Int, _ separatorIndex: Int)
+  -> Dependency?
+where T.Element == UInt8, T.Index == Int {
+  guard let isDirected = extractIsDirected(bytes, separatorIndex, end) else {
+    return nil
+  }
+
+  guard let fromComponent = extractTrimmedString(bytes, start, separatorIndex) else {
+    return nil
+  }
+
+  guard let toComponent = extractTrimmedString(bytes, separatorIndex + 2, end) else {
+    return nil
+  }
+
+  return Dependency(fromComponent: fromComponent, toComponent: toComponent, isDirected: isDirected)
+}
+
+/// Checks the second character of the separator to see if it's directed.
+/// It assumes we already checked for -- or ->, so it only checks for
+/// Whether it's greaterThan or not.
+@inline(__always)
+private func extractIsDirected<T: Collection>(_ bytes: T, _ separatorIndex: Int, _ end: Int)
+  -> Bool?
+where T.Element == UInt8, T.Index == Int {
+  let followingCharacter = separatorIndex + 1
+  guard followingCharacter < end else { return nil }
+  if bytes[followingCharacter] == kGreaterThan {
+    return true
+  }
+  return false
+}