feat(patterns): M.has(el,n) to support want patterns

Author: erights

packages/patterns/src/patterns/patternMatchers.js

@@ -1258,6 +1258,65 @@ const makePatternKit = () => {
     getRankCover: () => getPassStyleCover('tagged'),
   });
 
+  /** @type {MatchHelper} */
+  const matchHasHelper = Far('match:has helper', {
+    checkMatches: (
+      specimen,
+      [elementPatt, countPatt, limits = undefined],
+      check,
+    ) => {
+      let count = 0n;
+      const kind = kindOf(specimen, check);
+      switch (kind) {
+        case 'copyArray': {
+          for (const element of specimen) {
+            if (matches(element, elementPatt)) {
+              count += 1n;
+            }
+          }
+          break;
+        }
+        case 'copySet': {
+          for (const element of specimen.payload) {
+            if (matches(element, elementPatt)) {
+              count += 1n;
+            }
+          }
+          break;
+        }
+        case 'copyBag': {
+          for (const [element, num] of specimen.payload) {
+            if (matches(element, elementPatt)) {
+              count += num;
+            }
+          }
+          break;
+        }
+        default: {
+          return check(false, X`unexpected ${q(kind)}`);
+        }
+      }
+      const { decimalDigitsLimit } = limit(limits);
+      return (
+        applyLabelingError(
+          checkDecimalDigitsLimit,
+          [count, decimalDigitsLimit, check],
+          `${kind} matches`,
+        ) && checkMatches(count, countPatt, check, `${kind} matches`)
+      );
+    },
+
+    checkIsWellFormed: (payload, check) =>
+      checkIsWellFormedWithLimit(
+        payload,
+        harden([MM.pattern(), MM.pattern()]),
+        check,
+        'match:has payload',
+      ),
+
+    getRankCover: () => getPassStyleCover('tagged'),
+  });
+
   /** @type {MatchHelper} */
   const matchMapOfHelper = Far('match:mapOf helper', {
     checkMatches: (
@@ -1548,6 +1607,7 @@ const makePatternKit = () => {
     'match:recordOf': matchRecordOfHelper,
     'match:setOf': matchSetOfHelper,
     'match:bagOf': matchBagOfHelper,
+    'match:has': matchHasHelper,
     'match:mapOf': matchMapOfHelper,
     'match:splitArray': matchSplitArrayHelper,
     'match:splitRecord': matchSplitRecordHelper,
@@ -1702,6 +1762,8 @@ const makePatternKit = () => {
       makeLimitsMatcher('match:setOf', [keyPatt, limits]),
     bagOf: (keyPatt = M.any(), countPatt = M.any(), limits = undefined) =>
       makeLimitsMatcher('match:bagOf', [keyPatt, countPatt, limits]),
+    has: (elementPatt = M.any(), countPatt = MM.gte(1n), limits = undefined) =>
+      makeLimitsMatcher('match:has', [elementPatt, countPatt, limits]),
     mapOf: (keyPatt = M.any(), valuePatt = M.any(), limits = undefined) =>
       makeLimitsMatcher('match:mapOf', [keyPatt, valuePatt, limits]),
     splitArray: (base, optional = undefined, rest = undefined) =>

packages/patterns/src/types.js

@@ -380,6 +380,13 @@ export {};
  * `countPatt` is expected to rarely be useful,
  * but is provided to minimize surprise.
  *
+ * @property {(elementPatt?: Pattern,
+ *             countPatt?: Pattern,
+ *             limits?: Limits
+ * ) => Matcher} has
+ * Matches any array, CopySet, or CopyBag in which the bigint number of
+ * elements that match `elementPatt` is a number that matches `countPatt`.
+ *
  * @property {(keyPatt?: Pattern,
  *             valuePatt?: Pattern,
  *             limits?: Limits

packages/patterns/test/patterns.test.js

@@ -199,6 +199,12 @@ const runTests = (t, successCase, failCase) => {
 
     successCase(specimen, M.arrayOf(M.number()));
 
+    successCase(specimen, M.has(3));
+    successCase(specimen, M.has(3, 1n));
+    successCase(specimen, M.has(M.number(), 2n));
+    successCase(specimen, M.has('c', 0n));
+    successCase(specimen, M.has('c', M.nat()));
+
     failCase(specimen, [4, 3], '[3,4] - Must be: [4,3]');
     failCase(specimen, [3], '[3,4] - Must be: [3]');
     failCase(
@@ -227,6 +233,13 @@ const runTests = (t, successCase, failCase) => {
       M.arrayOf(M.string()),
       '[0]: number 3 - Must be a string',
     );
+
+    failCase(specimen, M.has(3, 1), 'copyArray matches: "[1n]" - Must be: 1');
+    failCase(
+      specimen,
+      M.has('c'),
+      'copyArray matches: "[0n]" - Must be >= "[1n]"',
+    );
   }
   {
     const specimen = { foo: 3, bar: 4 };
@@ -419,6 +432,12 @@ const runTests = (t, successCase, failCase) => {
     successCase(specimen, M.lte(makeCopySet([3, 4, 5])));
     successCase(specimen, M.setOf(M.number()));
 
+    successCase(specimen, M.has(3));
+    successCase(specimen, M.has(3, 1n));
+    successCase(specimen, M.has(M.number(), 2n));
+    successCase(specimen, M.has('c', 0n));
+    successCase(specimen, M.has('c', M.nat()));
+
     failCase(specimen, makeCopySet([]), '"[copySet]" - Must be: "[copySet]"');
     failCase(
       specimen,
@@ -440,6 +459,13 @@ const runTests = (t, successCase, failCase) => {
       M.setOf(M.string()),
       'set elements[0]: number 4 - Must be a string',
     );
+
+    failCase(specimen, M.has(3, 1), 'copySet matches: "[1n]" - Must be: 1');
+    failCase(
+      specimen,
+      M.has('c'),
+      'copySet matches: "[0n]" - Must be >= "[1n]"',
+    );
   }
   {
     const specimen = makeCopyBag([
@@ -472,6 +498,13 @@ const runTests = (t, successCase, failCase) => {
     );
     successCase(specimen, M.bagOf(M.string()));
     successCase(specimen, M.bagOf(M.string(), M.lt(5n)));
+    successCase(specimen, M.bagOf(M.string(), M.gte(2n)));
+
+    successCase(specimen, M.has('a'));
+    successCase(specimen, M.has('a', 2n));
+    successCase(specimen, M.has(M.string(), 5n));
+    successCase(specimen, M.has('c', 0n));
+    successCase(specimen, M.has('c', M.nat()));
 
     failCase(
       specimen,
@@ -509,6 +542,22 @@ const runTests = (t, successCase, failCase) => {
       M.bagOf(M.any(), M.gt(2n)),
       'bag counts[1]: "[2n]" - Must be > "[2n]"',
     );
+
+    failCase(
+      specimen,
+      M.has('a', 1n),
+      'copyBag matches: "[2n]" - Must be: "[1n]"',
+    );
+    failCase(
+      specimen,
+      M.has(M.string(), M.lte(4n)),
+      'copyBag matches: "[5n]" - Must be <= "[4n]"',
+    );
+    failCase(
+      specimen,
+      M.has('c'),
+      'copyBag matches: "[0n]" - Must be >= "[1n]"',
+    );
   }
   {
     const specimen = makeCopyMap([