1 files changed, 78 insertions, 0 deletions
diff --git a/src/ProtoGen/Helpers.cs b/src/ProtoGen/Helpers.cs
new file mode 100644
index 00000000..79a2912c
--- /dev/null
+++ b/src/ProtoGen/Helpers.cs
@@ -0,0 +1,78 @@
+using System;
+using System.Text;
+using Google.ProtocolBuffers.DescriptorProtos;
+using Google.ProtocolBuffers.Descriptors;
+namespace Google.ProtocolBuffers.ProtoGen {
+
+  /// <summary>
+  /// Helpers to resolve class names etc.
+  /// </summary>
+  internal static class Helpers {
+    internal static string UnderscoresToPascalCase(string input) {
+      return UnderscoresToPascalOrCamelCase(input, true);
+    }
+
+    internal static string UnderscoresToCamelCase(string input) {
+      return UnderscoresToPascalOrCamelCase(input, false);
+    }
+
+    internal static void WriteNamespaces(TextGenerator writer) {
+      writer.WriteLine("using pb = global::Google.ProtocolBuffers;");
+      writer.WriteLine("using pbc = global::Google.ProtocolBuffers.Collections;");
+      writer.WriteLine("using pbd = global::Google.ProtocolBuffers.Descriptors;");
+      writer.WriteLine("using scg = global::System.Collections.Generic;");
+    }
+
+    /// <summary>
+    /// Converts a string to Pascal or Camel case. The first letter is capitalized or
+    /// lower-cased depending on <paramref name="pascal"/> is true. 
+    /// After the first letter, any punctuation is removed but triggers capitalization
+    /// of the next letter. Digits are preserved but trigger capitalization of the next
+    /// letter.
+    /// All capitalisation is done in the invariant culture. 
+    /// </summary>
+    private static string UnderscoresToPascalOrCamelCase(string input, bool pascal) {
+      StringBuilder result = new StringBuilder();
+      bool capitaliseNext = pascal;
+      for (int i=0; i < input.Length; i++) {
+        char c = input[i];
+        if ('a' <= c && c <= 'z') {
+          if (capitaliseNext) {
+            result.Append(char.ToUpperInvariant(c));
+          } else {
+            result.Append(c);
+          }
+          capitaliseNext = false;
+        } else if ('A' <= c && c <= 'Z') {
+          if (i == 0 && !pascal) {
+            // Force first letter to lower-case unless explicitly told to
+            // capitalize it.
+            result.Append(char.ToLowerInvariant(c));
+          } else {
+            // Capital letters after the first are left as-is.
+            result.Append(c);
+          }
+          capitaliseNext = false;
+        } else if ('0' <= c && c <= '9') {
+          result.Append(c);
+          capitaliseNext = true;
+        } else {
+          capitaliseNext = true;
+        }
+      }
+      return result.ToString();
+    }
+
+    /// <summary>
+    /// Attempts to strip a suffix from a string, returning whether
+    /// or not the suffix was actually present.
+    /// </summary>
+    internal static bool StripSuffix(ref string text, string suffix) {
+      if (text.EndsWith(suffix)) {
+        text = text.Substring(0, text.Length - suffix.Length);
+        return true;
+      }
+      return false;
+    }
+  }
+}