Group syntax entities by combinator precedence

Author: frenic

src/parser.ts

@@ -11,15 +11,16 @@ export enum Component {
   Group,
 }
 
+// Higher number is higher precedence
 export enum Combinator {
   /** Components are mandatory and should appear in that order */
-  Juxtaposition,
+  Juxtaposition = 0,
   /** Components are mandatory but may appear in any order */
-  DoubleAmpersand,
+  DoubleAmpersand = 1,
   /** At least one of the components must be present, and they may appear in any order */
-  DoubleBar,
+  DoubleBar = 2,
   /** Exactly one of the components must be present */
-  SingleBar,
+  SingleBar = 3,
 }
 
 export enum Multiplier {
@@ -94,7 +95,6 @@ const REGEX_KEYWORD = /^([\w-]+)/g;
 
 export default function parse(syntax: string): EntityType[] {
   const levels: EntityType[][] = [[]];
-  const deepestLevel = () => levels[levels.length - 1];
   let previousMatchWasComponent = false;
   let entityMatch: RegExpExecArray | null;
   while ((entityMatch = REGEX_ENTITY.exec(syntax))) {
@@ -118,12 +118,12 @@ export default function parse(syntax: string): EntityType[] {
     } else if (value.indexOf(']') === 0) {
       const definitions = levels.pop();
       if (definitions) {
-        deepestLevel().push(componentGroupData(definitions, multiplierData(rawMultiplier)));
+        deepestLevel().push(componentGroupData(groupByPrecedence(definitions), multiplierData(rawMultiplier)));
       }
       previousMatchWasComponent = true;
       continue;
     } else {
-      if (previousMatchWasComponent === true) {
+      if (previousMatchWasComponent) {
         deepestLevel().push(combinatorData(Combinator.Juxtaposition));
       }
 
@@ -149,7 +149,27 @@ export default function parse(syntax: string): EntityType[] {
     deepestLevel().push({ entity: Entity.Unknown, multiplier: multiplierData(rawMultiplier) });
   }
 
-  return levels[0];
+  function deepestLevel() {
+    return levels[levels.length - 1];
+  }
+
+  return groupByPrecedence(levels[0]);
+}
+
+export function isFunction(entity: EntityType): entity is IFunction {
+  return entity.entity === Entity.Function;
+}
+
+export function isComponent(entity: EntityType): entity is ComponentType {
+  return entity.entity === Entity.Component;
+}
+
+export function isCombinator(entity: EntityType): entity is ICombinator {
+  return entity.entity === Entity.Combinator;
+}
+
+export function isQurlyBracetMultiplier(multiplier: MultiplierType): multiplier is IMultiplierQurlyBracet {
+  return multiplier.sign === Multiplier.QurlyBracet;
 }
 
 function combinatorData(combinator: Combinator, multiplier: MultiplierType | null = null): ICombinator {
@@ -173,7 +193,7 @@ function componentData(
   };
 }
 
-function componentGroupData(entities: EntityType[], multiplier: MultiplierType | null): ComponentType {
+function componentGroupData(entities: EntityType[], multiplier: MultiplierType | null = null): ComponentType {
   return {
     entity: Entity.Component,
     component: Component.Group,
@@ -203,3 +223,24 @@ function multiplierData(raw: string[]): MultiplierType | null {
       return null;
   }
 }
+
+function groupByPrecedence(entities: EntityType[]): EntityType[] {
+  for (let i = 0; i < entities.length; i++) {
+    const entity = entities[i];
+    if (isCombinator(entity)) {
+      for (let a = i; a >= 0; a--) {
+        const adjacentEntity = entities[a];
+        if (isCombinator(adjacentEntity) && adjacentEntity.combinator < entity.combinator) {
+          return groupByPrecedence([componentGroupData(entities.slice(0, i)), ...entities.slice(i)]);
+        }
+      }
+      for (let a = i; a < entities.length; a++) {
+        const subsequentEntity = entities[a];
+        if (isCombinator(subsequentEntity) && subsequentEntity.combinator < entity.combinator) {
+          return [...entities.slice(0, i + 1), componentGroupData(groupByPrecedence(entities.slice(i + 1)))];
+        }
+      }
+    }
+  }
+  return entities;
+}

src/typer.ts

@@ -8,8 +8,10 @@ import parse, {
   Entity,
   EntityType,
   ICombinator,
-  IFunction,
-  IMultiplierQurlyBracet,
+  isCombinator,
+  isComponent,
+  isFunction,
+  isQurlyBracetMultiplier,
   Multiplier,
   MultiplierType,
 } from './parser';
@@ -265,22 +267,6 @@ export default function typing(entities: EntityType[]): TypeType[] {
   return types;
 }
 
-function isFunction(entity: EntityType): entity is IFunction {
-  return entity.entity === Entity.Function;
-}
-
-function isComponent(entity: EntityType): entity is ComponentType {
-  return entity.entity === Entity.Component;
-}
-
-function isCombinator(entity: EntityType): entity is ICombinator {
-  return entity.entity === Entity.Combinator;
-}
-
-function isQurlyBracetMultiplier(multiplier: MultiplierType): multiplier is IMultiplierQurlyBracet {
-  return multiplier.sign === Multiplier.QurlyBracet;
-}
-
 function isMultiplied(multiplier: MultiplierType) {
   return (
     (isQurlyBracetMultiplier(multiplier) && (multiplier.min > 1 || multiplier.max === 1)) ||