feat: Add String type

.gitignore

@@ -131,3 +131,4 @@ dist
 
 # Editor settings
 .idea
+.vscode/launch.json

src/scalar/text.test.ts

@@ -0,0 +1,27 @@
+import { DataType } from '@apache-arrow/esnext-esm';
+import test from 'ava';
+
+import { Text } from './text.js';
+
+// eslint-disable-next-line unicorn/no-null
+[null, undefined].forEach((v) => {
+  test(`should set values to empty string when ${v} is passed`, (t) => {
+    const s = new Text(v);
+    t.is(s.value, '');
+    t.is(s.valid, false);
+    t.true(DataType.isUtf8(s.dataType));
+  });
+});
+
+['', 'test string', String('new string object'), new Text('new text object')].forEach((v, index) => {
+  test(`valid strings: '${v}' (${index})`, (t) => {
+    const s = new Text(v);
+    t.is(s.valid, true);
+    t.is(s.value, v.toString());
+    t.true(DataType.isUtf8(s.dataType));
+  });
+});
+
+test('should throw when unable to set value', (t) => {
+  t.throws(() => new Text({ value: {} }), { message: "Unable to set '[object Object]' as Text" });
+});

src/scalar/text.ts

@@ -0,0 +1,58 @@
+import { Utf8 as ArrowString } from '@apache-arrow/esnext-esm';
+
+import { Scalar } from './scalar.js';
+import { isInvalid, NULL_VALUE } from './util.js';
+
+export class Text implements Scalar<string> {
+  private _valid = false;
+  private _value = '';
+
+  public constructor(v: unknown) {
+    this.value = v;
+    return this;
+  }
+
+  public get dataType() {
+    return new ArrowString();
+  }
+
+  public get valid(): boolean {
+    return this._valid;
+  }
+
+  public get value(): string {
+    return this._value;
+  }
+
+  public set value(value: unknown) {
+    if (isInvalid(value)) {
+      this._valid = false;
+      return;
+    }
+
+    switch (typeof value) {
+      case 'object': {
+        if (value !== undefined && value !== null && Object.hasOwn(value, 'toString')) {
+          this._value = value.toString();
+          this._valid = true;
+          return;
+        }
+        break;
+      }
+      case 'string': {
+        this._value = value.toString();
+        this._valid = true;
+        return;
+      }
+    }
+    throw new Error(`Unable to set '${value}' as Text`);
+  }
+
+  public toString = (): string => {
+    if (this._valid) {
+      return this._value.toString();
+    }
+
+    return NULL_VALUE;
+  };
+}

tsconfig.json

@@ -4,6 +4,7 @@
     "allowJs": true,
     "declaration": true,
     "outDir": "dist",
-    "sourceMap": true
+    "sourceMap": true,
+    "lib": ["esnext", "dom"]
   }
 }