From c1c7930d8a7b0f53ed5429d0e77692a9a5715be8 Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Mon, 19 Mar 2018 17:23:05 +0200
Subject: [PATCH] isEmpty, type fix and minor tweaks (#137)

---
 index.d.ts          |  4 ++++
 src/Bundle.js       | 27 +++++++++++++-------------
 src/MagicString.js  | 47 ++++++++++++++++++++++++++++++++++++++-------
 test/MagicString.js | 19 ++++++++++++++++++
 4 files changed, 76 insertions(+), 21 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index ec23bed..5d9e1e1 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -48,6 +48,7 @@ export class Bundle {
   trim(charType?: string): Bundle;
   trimStart(charType?: string): Bundle;
   trimEnd(charType?: string): Bundle;
+  isEmpty(): boolean;
 }
 
 export type ExclusionRange = [ number, number ];
@@ -90,6 +91,9 @@ export default class MagicString {
   remove(start: number, end: number): MagicString;
   slice(start: number, end: number): string;
   snip(start: number, end: number): MagicString;
+  trim(): MagicString;
+
+  isEmpty(): boolean;
 
   original: string;
 }
diff --git a/src/Bundle.js b/src/Bundle.js
index 1ac6cdb..779676f 100644
--- a/src/Bundle.js
+++ b/src/Bundle.js
@@ -195,8 +195,7 @@ export default class Bundle {
 				indentStart //: trailingNewline || /\r?\n$/.test( separator )  //true///\r?\n/.test( separator )
 			});
 
-			// TODO this is a very slow way to determine this
-			trailingNewline = source.content.toString().slice(0, -1) === '\n';
+			trailingNewline = source.content.lastChar() === '\n';
 		});
 
 		if (this.intro) {
@@ -228,6 +227,14 @@ export default class Bundle {
 		return this.intro + body;
 	}
 
+	isEmpty () {
+		if (this.intro.length && this.intro.trim())
+			return false;
+		if (this.sources.some(source => !source.content.isEmpty()))
+			return false;
+		return true;
+	}
+
 	trimLines() {
 		return this.trim('[\\r\\n]');
 	}
@@ -245,15 +252,11 @@ export default class Bundle {
 			let i = 0;
 
 			do {
-				source = this.sources[i];
-
+				source = this.sources[i++];
 				if (!source) {
 					break;
 				}
-
-				source.content.trimStart(charType);
-				i += 1;
-			} while (source.content.toString() === ''); // TODO faster way to determine non-empty source?
+			} while (!source.content.trimStartAborted(charType));
 		}
 
 		return this;
@@ -266,16 +269,12 @@ export default class Bundle {
 		let i = this.sources.length - 1;
 
 		do {
-			source = this.sources[i];
-
+			source = this.sources[i--];
 			if (!source) {
 				this.intro = this.intro.replace(rx, '');
 				break;
 			}
-
-			source.content.trimEnd(charType);
-			i -= 1;
-		} while (source.content.toString() === ''); // TODO faster way to determine non-empty source?
+		} while (!source.content.trimEndAborted(charType));
 
 		return this;
 	}
diff --git a/src/MagicString.js b/src/MagicString.js
index 3aa65b9..e73353a 100644
--- a/src/MagicString.js
+++ b/src/MagicString.js
@@ -459,6 +459,19 @@ export default class MagicString {
 		return this;
 	}
 
+	lastChar() {
+		let chunk = this.lastChunk;
+		do {
+			if (chunk.outro.length)
+				return chunk.outro[chunk.outro.length - 1];
+			if (chunk.content.length)
+				return chunk.content[chunk.content.length - 1];
+			if (chunk.intro.length)
+				return chunk.intro[chunk.intro.length - 1];
+		} while (chunk = chunk.previous);
+		return '';
+	}
+
 	slice(start = 0, end = this.original.length) {
 		while (start < 0) start += this.original.length;
 		while (end < 0) end += this.original.length;
@@ -568,6 +581,17 @@ export default class MagicString {
 		return str + this.outro;
 	}
 
+	isEmpty() {
+		let chunk = this.firstChunk;
+		do {
+			if (chunk.intro.length && chunk.intro.trim() ||
+					chunk.content.length && chunk.content.trim() ||
+					chunk.outro.length && chunk.outro.trim())
+				return false;
+		} while (chunk = chunk.next);
+		return true;
+	}
+
 	trimLines() {
 		return this.trim('[\\r\\n]');
 	}
@@ -576,11 +600,11 @@ export default class MagicString {
 		return this.trimStart(charType).trimEnd(charType);
 	}
 
-	trimEnd(charType) {
+	trimEndAborted(charType) {
 		const rx = new RegExp((charType || '\\s') + '+$');
 
 		this.outro = this.outro.replace(rx, '');
-		if (this.outro.length) return this;
+		if (this.outro.length) return true;
 
 		let chunk = this.lastChunk;
 
@@ -599,18 +623,22 @@ export default class MagicString {
 				this.byEnd[chunk.next.end] = chunk.next;
 			}
 
-			if (aborted) return this;
+			if (aborted) return true;
 			chunk = chunk.previous;
 		} while (chunk);
 
-		return this;
+		return false;
 	}
 
-	trimStart(charType) {
+	trimEnd(charType) {
+		this.trimEndAborted(charType);
+		return this;
+	}
+	trimStartAborted(charType) {
 		const rx = new RegExp('^' + (charType || '\\s') + '+');
 
 		this.intro = this.intro.replace(rx, '');
-		if (this.intro.length) return this;
+		if (this.intro.length) return true;
 
 		let chunk = this.firstChunk;
 
@@ -627,10 +655,15 @@ export default class MagicString {
 				this.byEnd[chunk.next.end] = chunk.next;
 			}
 
-			if (aborted) return this;
+			if (aborted) return true;
 			chunk = chunk.next;
 		} while (chunk);
 
+		return false;
+	}
+
+	trimStart(charType) {
+		this.trimStartAborted(charType);
 		return this;
 	}
 }
diff --git a/test/MagicString.js b/test/MagicString.js
index d1e38f0..5726f8e 100644
--- a/test/MagicString.js
+++ b/test/MagicString.js
@@ -1172,4 +1172,23 @@ describe( 'MagicString', () => {
 			assert.equal( s.toString(), '   abcdefghijkl   ' );
 		});
 	});
+
+	describe( 'isEmpty', () => {
+		it( 'should support isEmpty', () => {
+			const s = new MagicString( ' abcde   fghijkl ' );
+
+			assert.equal( s.isEmpty(), false );
+
+			s.prepend( '  ' );
+			s.append( '  ' );
+			s.remove( 1, 6 );
+			s.remove( 9, 15 );
+
+			assert.equal( s.isEmpty(), false );
+
+			s.remove( 15, 16 );
+
+			assert.equal( s.isEmpty(), true );
+		});
+	});
 });