Optimize format of type list id strings used in maps

ahejlsberg · ahejlsberg · commit 9d4547c5d084 · 2016-08-09T16:33:45.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -4941,24 +4941,27 @@ namespace ts {
         }
 
         function getTypeListId(types: Type[]) {
+            let result = "";
             if (types) {
-                switch (types.length) {
-                    case 1:
-                        return "" + types[0].id;
-                    case 2:
-                        return types[0].id + "," + types[1].id;
-                    default:
-                        let result = "";
-                        for (let i = 0; i < types.length; i++) {
-                            if (i > 0) {
-                                result += ",";
-                            }
-                            result += types[i].id;
-                        }
-                        return result;
+                const length = types.length;
+                let i = 0;
+                while (i < length) {
+                    const startId = types[i].id;
+                    let count = 1;
+                    while (i + count < length && types[i + count].id === startId + count) {
+                        count++;
+                    }
+                    if (result.length) {
+                        result += ",";
+                    }
+                    result += startId;
+                    if (count > 1) {
+                        result += ":" + count;
+                    }
+                    i += count;
                 }
             }
-            return "";
+            return result;
         }
 
         // This function is used to propagate certain flags when creating new object type references and union types.

Original file line number	Original file line	Diff line number	Diff line change
`@@ -4941,24 +4941,27 @@ namespace ts {`
`4941`	`}`	`4941`	`}`
`4942`		`4942`
`4943`	`function getTypeListId(types: Type[]) {`	`4943`	`function getTypeListId(types: Type[]) {`
		`4944`	`+ let result = "";`
`4944`	`if (types) {`	`4945`	`if (types) {`
`4945`	`- switch (types.length) {`	`4946`	`+ const length = types.length;`
`4946`	`- case 1:`	`4947`	`+ let i = 0;`
`4947`	`- return "" + types[0].id;`	`4948`	`+ while (i < length) {`
`4948`	`- case 2:`	`4949`	`+ const startId = types[i].id;`
`4949`	`- return types[0].id + "," + types[1].id;`	`4950`	`+ let count = 1;`
`4950`	`- default:`	`4951`	`+ while (i + count < length && types[i + count].id === startId + count) {`
`4951`	`- let result = "";`	`4952`	`+ count++;`
`4952`	`- for (let i = 0; i < types.length; i++) {`	`4953`	`+ }`
`4953`	`- if (i > 0) {`	`4954`	`+ if (result.length) {`
`4954`	`- result += ",";`	`4955`	`+ result += ",";`
`4955`	`- }`	`4956`	`+ }`
`4956`	`- result += types[i].id;`	`4957`	`+ result += startId;`
`4957`	`- }`	`4958`	`+ if (count > 1) {`
`4958`	`- return result;`	`4959`	`+ result += ":" + count;`
		`4960`	`+ }`
		`4961`	`+ i += count;`
`4959`	`}`	`4962`	`}`
`4960`	`}`	`4963`	`}`
`4961`	`- return "";`	`4964`	`+ return result;`
`4962`	`}`	`4965`	`}`
`4963`		`4966`
`4964`	`// This function is used to propagate certain flags when creating new object type references and union types.`	`4967`	`// This function is used to propagate certain flags when creating new object type references and union types.`