Add the first class!

- Begins implementation of the ContentLine class as well as
  starts the util module.

PROGRESS.md

@@ -116,6 +116,18 @@ breaks.
   - All other property values, unless otherwise stated, are **case-sensitive**.
 
 #### 3.1.1. List and Field Separators
+
+  - Properties which allow lists of values will have those values separated by
+  the **COMMA** character.
+
+  - There is no significance to the order of values in a list.
+
+  - For values specified in quoted-strings, each quoted-string should be
+  separated by a **COMMA** character.
+
+  - Some property values are defined in terms of multiple parts. Each value
+  **MUST** be separated by a **SEMICOLON** character.
+
 #### 3.1.2. Multiple Values
 #### 3.1.3. Binary Content
 #### 3.1.4. Character Set

src/ContentLine.ts

+import { isAlpha } from "./util";
+
+/**
+ * Implementation of a Content Line from RFC 5545
+ *
+ * @author Mark Stenglein <mark@stengle.in>
+ *
+ * Chapter 3.1 defines the content line. This implementation will use it as an
+ * abstract class which can be extended later by the specific content types.
+ *
+ * This class defines all of the general features specified by the chapter,
+ * while leaving the specific features required by individual component objects
+ * unfilled.
+ */
+export class ContentLine {
+    private _name: string;
+    private _param: string;
+    private _value: string;
+
+    constructor(inName: string, inParam: string, inValue: string) {
+        this.name = inName;
+        this.param = inParam;
+        this.value = inValue;
+    }
+
+    /* Getters */
+
+    get name(): string {
+        return this._name;
+    }
+
+    get param(): string {
+        return this._param;
+    }
+
+    get value(): string {
+        return this._value;
+    }
+
+    /* Setters */
+
+    set name(newName: string) {
+        if (isAlpha(newName)) {
+            this._name = newName;
+        }
+        else {
+            throw new TypeError("'name' must be alphabetic!")
+        }
+    }
+
+    set param(newParam: string) {
+        this._param = newParam;
+    }
+
+    set value(newValue: string) {
+        if (isAlpha(newValue)) {
+            this._value = newValue;
+        }
+    }
+} 
\ No newline at end of file

src/util.ts

+export function isAlpha(input: string): boolean {
+    return /^[a-zA-Z]+$/.test(input);
+}
\ No newline at end of file

tsconfig.json

 {
     "files": [
-        "src/**/*.ts",
+        "src/**/*.ts"
     ],
     "compilerOptions": {
         "module": "commonjs",
         "declaration": true,
         "noImplicitAny": true,
-        "target": "es5"
+        "target": "es2015"
     }
 }