feat: add support for array coalescing (#15)

* feat: add support for array coalescing Added support ??? as coalesing using arrays. This is for getting rid of getOneByPaths to further improve the performance.
rudderlabs · Dec 1, 2022 · 2f3bf0f · 2f3bf0f
1 parent 02ffb67
commit 2f3bf0f
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Showing 5 changed files with 79 additions and 33 deletions.
diff --git a/src/lexer.ts b/src/lexer.ts
@@ -502,16 +502,25 @@ export class JsonTemplateLexer {
     }
   }
 
-  private scanPunctuatorForRepeatedTokens(): Token | undefined {
-    let start = this.idx,
-      ch1 = this.codeChars[this.idx],
-      ch2 = this.codeChars[this.idx + 1];
+  private scanPunctuatorForRepeatedTokens(
+    validSymbols: string,
+    numRepeations = 2,
+  ): Token | undefined {
+    let start = this.idx;
+    let ch = this.codeChars[this.idx];
+    let tokenVal = ch;
+    for (let i = 1; i < numRepeations; i++) {
+      if (this.codeChars[this.idx + i] !== ch) {
+        return;
+      }
+      tokenVal += ch;
+    }
 
-    if (ch1 === ch2 && '|&*.=>?<'.includes(ch1)) {
-      this.idx += 2;
+    if (validSymbols.includes(ch)) {
+      this.idx += numRepeations;
       return {
         type: TokenType.PUNCT,
-        value: ch1 + ch2,
+        value: tokenVal,
         range: [start, this.idx],
       };
     }
@@ -550,7 +559,8 @@ export class JsonTemplateLexer {
       this.scanPunctuatorForDots() ||
       this.scanPunctuatorForQuestionMarks() ||
       this.scanPunctuatorForEquality() ||
-      this.scanPunctuatorForRepeatedTokens() ||
+      this.scanPunctuatorForRepeatedTokens('?', 3) ||
+      this.scanPunctuatorForRepeatedTokens('|&*.=>?<', 2) ||
       this.scanSingleCharPunctuators()
     );
   }

diff --git a/src/parser.ts b/src/parser.ts
@@ -106,7 +106,7 @@ export class JsonTemplateParser {
       case OperatorType.CONDITIONAL:
         return this.parseAssignmentExpr();
       case OperatorType.ASSIGNMENT:
-        return this.parseCoalescingExpr();
+        return this.parseCoalesceExpr();
       case OperatorType.COALESCING:
         return this.parseLogicalORExpr();
       case OperatorType.OR:
@@ -366,26 +366,8 @@ export class JsonTemplateParser {
     };
   }
 
-  private combineObjectFilters(objectFilters: ObjectFilterExpression[]): ObjectFilterExpression[] {
-    if (objectFilters.length <= 1) {
-      return objectFilters;
-    }
-    const expr1 = objectFilters.shift() as ObjectFilterExpression;
-    const expr2 = this.combineObjectFilters(objectFilters);
-    return [
-      {
-        type: SyntaxType.OBJECT_FILTER_EXPR,
-        filter: {
-          type: SyntaxType.LOGICAL_AND_EXPR,
-          op: '&&',
-          args: [expr1.filter, expr2[0].filter],
-        },
-      },
-    ];
-  }
-
   private parseObjectFiltersExpr(): (ObjectFilterExpression | IndexFilterExpression)[] {
-    const objectFilters: ObjectFilterExpression[] = [];
+    const objectFilters: Expression[] = [];
     const indexFilters: IndexFilterExpression[] = [];
 
     while (this.lexer.match('{')) {
@@ -394,15 +376,24 @@ export class JsonTemplateParser {
       if (expr.type === SyntaxType.OBJECT_INDEX_FILTER_EXPR) {
         indexFilters.push(expr as IndexFilterExpression);
       } else {
-        objectFilters.push(expr as ObjectFilterExpression);
+        objectFilters.push(expr.filter);
       }
       this.lexer.expect('}');
       if (this.lexer.match('.') && this.lexer.match('{', 1)) {
         this.lexer.ignoreTokens(1);
       }
     }
 
-    return [...this.combineObjectFilters(objectFilters), ...indexFilters];
+    if (!objectFilters.length) {
+      return indexFilters;
+    }
+
+    const objectFilter: ObjectFilterExpression = {
+      type: SyntaxType.OBJECT_FILTER_EXPR,
+      filter: this.combineExpressionsAsBinaryExpr(objectFilters, SyntaxType.LOGICAL_AND_EXPR, '&&'),
+    };
+
+    return [objectFilter, ...indexFilters];
   }
 
   private parseConditionalExpr(): ConditionalExpression | Expression {
@@ -451,14 +442,42 @@ export class JsonTemplateParser {
     };
   }
 
-  private parseCoalescingExpr(): BinaryExpression | Expression {
+  private combineExpressionsAsBinaryExpr(
+    values: Expression[],
+    type: SyntaxType,
+    op: string,
+  ): BinaryExpression | Expression {
+    if (!values?.length) {
+      throw new JsonTemplateParserError('expected at least 1 expression');
+    }
+    if (values.length === 1) {
+      return values[0];
+    }
+    return {
+      type,
+      op,
+      args: [values.shift(), this.combineExpressionsAsBinaryExpr(values, type, op)],
+    };
+  }
+
+  private parseArrayCoalesceExpr(): BinaryExpression | Expression {
+    this.lexer.ignoreTokens(1);
+    const expr = this.parseArrayExpr();
+    return this.combineExpressionsAsBinaryExpr(
+      expr.elements,
+      SyntaxType.LOGICAL_COALESCE_EXPR,
+      '??',
+    );
+  }
+
+  private parseCoalesceExpr(): BinaryExpression | Expression {
     let expr = this.parseNextExpr(OperatorType.COALESCING);
 
     if (this.lexer.match('??')) {
       return {
         type: SyntaxType.LOGICAL_COALESCE_EXPR,
         op: this.lexer.value(),
-        args: [expr, this.parseCoalescingExpr()],
+        args: [expr, this.parseCoalesceExpr()],
       };
     }
 
@@ -963,6 +982,10 @@ export class JsonTemplateParser {
       return this.parseNumber();
     }
 
+    if (this.lexer.match('???')) {
+      return this.parseArrayCoalesceExpr();
+    }
+
     if (this.lexer.match('.') && this.lexer.matchINT(1) && !this.lexer.match('.', 2)) {
       return this.parseFloatingNumber();
     }

diff --git a/test/scenarios/bad_templates/bad_array_coalese_expr.jt b/test/scenarios/bad_templates/bad_array_coalese_expr.jt
@@ -0,0 +1 @@
+??? []
diff --git a/test/scenarios/bad_templates/data.ts b/test/scenarios/bad_templates/data.ts
@@ -1,6 +1,10 @@
 import { Sceanario } from '../../types';
 
 export const data: Sceanario[] = [
+  {
+    templatePath: 'bad_array_coalese_expr.jt',
+    error: 'expected at least 1 expression',
+  },
   {
     templatePath: 'bad_async_usage.jt',
     error: 'Unexpected token',

diff --git a/test/scenarios/logics/template.jt b/test/scenarios/logics/template.jt
@@ -1 +1,9 @@
-[2 && 3, 0 && 3, 2 || 3, 0 || 3, 0 ?? 3, null ?? undefined ?? 3, !false, !!true];
+[   
+    2 && 3, 
+    0 && 3, 
+    2 || 3, 
+    0 || 3, 
+    0 ?? 3, 
+    ??? [null, undefined, 3],
+    !false, !!true,
+];