Add support for 'lest' and 'and' in assignment

src/grammars/sonic-weave.pegjs

@@ -508,8 +508,22 @@ ExpressionStatement
 Expression
   = LestExpression
 
+AssigningOperator
+  = LestOperator
+  / CoalescingOperator
+  / ConjunctOperator
+  / RoundingOperator
+  / ExtremumOperator
+  / AdditiveOperator
+  / MiscOperator
+  / MultiplicativeOperator
+  / ExponentiationOperator
+  / FractionOperator
+
+LestOperator = $LestToken
+
 LestExpression
-  = head: ConditionalExpression tail: (__ @$LestToken _ @LestExpression)* {
+  = head: ConditionalExpression tail: (__ @LestOperator _ @LestExpression)* {
     return tail.reduce(operatorReducerLite, head);
   }
 
@@ -527,27 +541,19 @@ ConditionalExpression
     );
   }
 
-AssigningOperator
-  = CoalescingOperator
-  / RoundingOperator
-  / ExtremumOperator
-  / AdditiveOperator
-  / MiscOperator
-  / MultiplicativeOperator
-  / ExponentiationOperator
-  / FractionOperator
-
 CoalescingOperator = '??' / $(OrToken)
 
 CoalescingExpression
   = head: ConjunctionExpression tail: (__ @CoalescingOperator _ @ConjunctionExpression)* {
     return tail.reduce(operatorReducerLite, head);
   }
 
+ConjunctOperator = $AndToken
+
 Conjunct = NotExpression / RelationalExpression
 
 ConjunctionExpression
-  = head: NotExpression tail: (__ @$AndToken _ @NotExpression)* {
+  = head: NotExpression tail: (__ @ConjunctOperator _ @NotExpression)* {
     return tail.reduce(operatorReducerLite, head);
   }
 

src/parser/__tests__/expression.spec.ts

@@ -1482,6 +1482,14 @@ describe('SonicWeave expression evaluator', () => {
     expect(pi.valueOf()).toBeCloseTo(Math.PI);
   });
 
+  it('has inline analogue of assignment inside try..catch', () => {
+    const pi = evaluate(
+      'let halfTau = PI;halfTau lest= fraction(halfTau);halfTau'
+    ) as Interval;
+    expect(pi.value.isFractional()).toBe(false);
+    expect(pi.valueOf()).toBeCloseTo(Math.PI);
+  });
+
   it('has atan2 with swapped arguments', () => {
     const interval = evaluate('atanXY(S5, -E)') as Interval;
     expect(interval.domain).toBe('linear');
@@ -2036,4 +2044,9 @@ describe('SonicWeave expression evaluator', () => {
       'Only identifiers, array elements or record values may be incremented or decremented.'
     );
   });
+
+  it('supports assigning boolean and', () => {
+    const {fraction} = parseSingle('let foo = 1;foo and= 0;foo');
+    expect(fraction).toBe('0');
+  });
 });