Pattern Matching

src/stdlib.js

@@ -11,6 +11,29 @@ export const lightscriptImports = {
   "bitwiseZeroFillRightShift": "inline",
 };
 
+export const runtimeHelpers = {
+  hasProps: function hasProps(obj) {
+    if (obj == null) return false;
+    if (typeof obj !== "object" && typeof obj !== "function") return false;
+    let i = arguments.length;
+    while (--i > 0) {
+      if (!(arguments[i] in obj)) return false;
+    }
+    return true;
+  },
+  hasLength: function hasLength(arr, minLength, maxLength) {
+    minLength = minLength || 0;
+    maxLength = maxLength != null ? maxLength : Number.MAX_SAFE_INTEGER;
+    return (
+      arr != null &&
+      typeof arr !== "function" &&
+      arr.length === arr.length|0 &&
+      arr.length >= minLength &&
+      arr.length <= maxLength
+    );
+  },
+};
+
 export const everyLodashMethod = [
   "add",
   "after",

test/fixtures/match/arr-pattern/actual.js

@@ -0,0 +1,18 @@
+match x:
+  | with []:
+    "empty"
+  | with [ a, b ]:
+    a - b
+  | with [ a, b = 2 ]:
+    a + b - 2
+  | with [ a, ...b ]:
+    b.concat(a)
+  | with [
+      [
+        b
+        d = 'e'
+      ]
+      [ g, , h ]
+      ...j
+  ]:
+    [b, d, g, ...j].join('')

test/fixtures/match/arr-pattern/exec.js

@@ -0,0 +1,92 @@
+assert.equal(
+  "empty",
+  match []:
+    | with []:
+      "empty"
+)
+assert.equal(
+  "empty",
+  match []:
+    | with []:
+      "empty"
+)
+assert.equal(
+  undefined,
+  match []:
+    | with [a]:
+      a + 1
+)
+assert.equal(
+  undefined,
+  match [1]:
+    | with [a, b]:
+      a + b
+)
+assert.equal(
+  5,
+  match [1]:
+    | with [a, b = 4]:
+      a + b
+)
+assert.equal(
+  3,
+  match [1, 2]:
+    | with [a, b]:
+      a + b
+)
+assert.equal(
+  4,
+  match [1, 2, 3]:
+    | with [a,, b]:
+      a + b
+)
+assert.equal(
+  undefined,
+  match [1, 2]:
+    | with [a,, b]:
+      a + b
+)
+assert.deepEqual(
+  [2, 3, 1],
+  match [1, 2, 3]:
+    | with [a, ...b]:
+      b.concat(a)
+)
+assert.deepEqual(
+  [1, 4],
+  match [4]:
+    | with [a, b = 1, ...c]:
+      c.concat([b, a])
+)
+assert.deepEqual(
+  [6, 7, 5, 4],
+  match [4, 5, 6, 7]:
+    | with [a, b = 1, ...c]:
+      c.concat([b, a])
+)
+assert.deepEqual(
+  [1, 2, 4, 6, 7, 8],
+  match [[1], [4, 5, 6], 7, 8]:
+    | with [
+        [
+          b
+          d = 2
+        ]
+        [ g, , h ]
+        ...j
+    ]:
+      [b, d, g, h, ...j]
+)
+assert.deepEqual(
+  undefined,
+  match [[1], [4, 5], 7, 8]:
+    | with [
+        [
+          b
+          d = 2
+        ]
+        [ g, , h ]
+        ...j
+    ]:
+      [b, d, g, h, ...j]
+)

test/fixtures/match/arr-pattern/expected.js

@@ -0,0 +1,23 @@
+function _hasLength(arr, minLength, maxLength) { minLength = minLength || 0; maxLength = maxLength != null ? maxLength : Number.MAX_SAFE_INTEGER; return arr != null && typeof arr !== "function" && arr.length === arr.length | 0 && arr.length >= minLength && arr.length <= maxLength; }
+
+if (_hasLength(x, 0, 0)) {
+  const [] = x;
+
+  "empty";
+} else if (_hasLength(x, 2, 2)) {
+  const [a, b] = x;
+
+  a - b;
+} else if (_hasLength(x, 1, 2)) {
+  const [a, b = 2] = x;
+
+  a + b - 2;
+} else if (_hasLength(x, 1)) {
+  const [a, ...b] = x;
+
+  b.concat(a);
+} else if (_hasLength(x, 2) && _hasLength(x[0], 1, 2) && _hasLength(x[1], 3, 3)) {
+  const [[b, d = 'e'], [g,, h], ...j] = x;
+
+  [b, d, g, ...j].join('');
+}

test/fixtures/match/as-call-expression/actual.js

@@ -0,0 +1,7 @@
+z = match foo.bar() as y:
+  | y < 1: "lt one"
+  | y + 1 == 1: "eq zero"
+  | y == 2: "eq two"
+  | y~f(): "f(x) truthy"
+  | y.prop: "has prop"
+  | y.0: "has first child"

test/fixtures/match/as-call-expression/expected.js

@@ -0,0 +1,15 @@
+const z = (y => {
+  if (y < 1) {
+      return "lt one";
+    } else if (y + 1 === 1) {
+      return "eq zero";
+    } else if (y === 2) {
+      return "eq two";
+    } else if (f(y)) {
+      return "f(x) truthy";
+    } else if (y.prop) {
+      return "has prop";
+    } else if (y[0]) {
+      return "has first child";
+    }
+})(foo.bar());

test/fixtures/match/as-call-statement/actual.js

@@ -0,0 +1,7 @@
+match foo() as y:
+  | y < 1: "lt one"
+  | y + 1 == 1: "eq zero"
+  | y == 2: "eq two"
+  | y~f(): "f(y) truthy"
+  | y.prop: "has prop"
+  | y.0: "has first child"

test/fixtures/match/as-call-statement/expected.js

@@ -0,0 +1,15 @@
+const y = foo();
+
+if (y < 1) {
+    "lt one";
+  } else if (y + 1 === 1) {
+    "eq zero";
+  } else if (y === 2) {
+    "eq two";
+  } else if (f(y)) {
+    "f(y) truthy";
+  } else if (y.prop) {
+    "has prop";
+  } else if (y[0]) {
+    "has first child";
+  }

test/fixtures/match/as-identifier-expression/actual.js

@@ -0,0 +1,7 @@
+z = match x as y:
+  | y < 1: "lt one"
+  | y + 1 == 1: "eq zero"
+  | y == 2: "eq two"
+  | y~f(): "f(x) truthy"
+  | y.prop: "has prop"
+  | y.0: "has first child"

test/fixtures/match/as-identifier-expression/expected.js

@@ -0,0 +1,15 @@
+const z = (y => {
+  if (y < 1) {
+      return "lt one";
+    } else if (y + 1 === 1) {
+      return "eq zero";
+    } else if (y === 2) {
+      return "eq two";
+    } else if (f(y)) {
+      return "f(x) truthy";
+    } else if (y.prop) {
+      return "has prop";
+    } else if (y[0]) {
+      return "has first child";
+    }
+})(x);

test/fixtures/match/as-identifier-statement-body-reference/actual.js

@@ -0,0 +1,3 @@
+match x:
+  | 1: "foo"
+  | "1": it

test/fixtures/match/as-identifier-statement-body-reference/expected.js

@@ -0,0 +1,7 @@
+const it = x;
+
+if (it === 1) {
+    "foo";
+  } else if (it === "1") {
+    it;
+  }

test/fixtures/match/as-identifier-statement-not-referenced/actual.js

@@ -0,0 +1,3 @@
+match x:
+  | 1: "foo"
+  | "1": "bar"

test/fixtures/match/as-identifier-statement-not-referenced/expected.js

@@ -0,0 +1,5 @@
+if (x === 1) {
+    "foo";
+  } else if (x === "1") {
+    "bar";
+  }

test/fixtures/match/as-identifier-statement/actual.js

@@ -0,0 +1,7 @@
+match x as y:
+  | y < 1: "lt one"
+  | y + 1 == 1: "eq zero"
+  | y == 2: "eq two"
+  | y~f(): "f(x) truthy"
+  | y.prop: "has prop"
+  | y.0: "has first child"

test/fixtures/match/as-identifier-statement/expected.js

@@ -0,0 +1,15 @@
+const y = x;
+
+if (y < 1) {
+    "lt one";
+  } else if (y + 1 === 1) {
+    "eq zero";
+  } else if (y === 2) {
+    "eq two";
+  } else if (f(y)) {
+    "f(x) truthy";
+  } else if (y.prop) {
+    "has prop";
+  } else if (y[0]) {
+    "has first child";
+  }

test/fixtures/match/as-it-call-expression/actual.js

@@ -0,0 +1,7 @@
+z = match foo.bar():
+  | it < 1: "lt one"
+  | it + 1 == 1: "eq zero"
+  | it == 2: "eq two"
+  | it~f(): "f(x) truthy"
+  | it.prop: "has prop"
+  | it.0: "has first child"

test/fixtures/match/as-it-call-expression/expected.js

@@ -0,0 +1,15 @@
+const z = (it => {
+  if (it < 1) {
+      return "lt one";
+    } else if (it + 1 === 1) {
+      return "eq zero";
+    } else if (it === 2) {
+      return "eq two";
+    } else if (f(it)) {
+      return "f(x) truthy";
+    } else if (it.prop) {
+      return "has prop";
+    } else if (it[0]) {
+      return "has first child";
+    }
+})(foo.bar());

test/fixtures/match/as-it-call-statement/actual.js

@@ -0,0 +1,7 @@
+match foo():
+  | it < 1: "lt one"
+  | it + 1 == 1: "eq zero"
+  | it == 2: "eq two"
+  | it~f(): "f(x) truthy"
+  | it.prop: "has prop"
+  | it.0: "has first child"

test/fixtures/match/as-it-call-statement/expected.js

@@ -0,0 +1,15 @@
+const it = foo();
+
+if (it < 1) {
+    "lt one";
+  } else if (it + 1 === 1) {
+    "eq zero";
+  } else if (it === 2) {
+    "eq two";
+  } else if (f(it)) {
+    "f(x) truthy";
+  } else if (it.prop) {
+    "has prop";
+  } else if (it[0]) {
+    "has first child";
+  }

test/fixtures/match/as-it-identifier-expression/actual.js

@@ -0,0 +1,7 @@
+z = match x:
+  | it < 1: "lt one"
+  | it + 1 == 1: "eq zero"
+  | it == 2: "eq two"
+  | it~f(): "f(x) truthy"
+  | it.prop: "has prop"
+  | it.0: "has first child"

test/fixtures/match/as-it-identifier-expression/expected.js

@@ -0,0 +1,15 @@
+const z = (it => {
+  if (it < 1) {
+      return "lt one";
+    } else if (it + 1 === 1) {
+      return "eq zero";
+    } else if (it === 2) {
+      return "eq two";
+    } else if (f(it)) {
+      return "f(x) truthy";
+    } else if (it.prop) {
+      return "has prop";
+    } else if (it[0]) {
+      return "has first child";
+    }
+})(x);

test/fixtures/match/as-it-identifier-statement/actual.js

@@ -0,0 +1,7 @@
+match x:
+  | it < 1: "lt one"
+  | it + 1 == 1: "eq zero"
+  | it == 2: "eq two"
+  | it~f(): "f(x) truthy"
+  | it.prop: "has prop"
+  | it.0: "has first child"

test/fixtures/match/as-it-identifier-statement/expected.js

@@ -0,0 +1,15 @@
+const it = x;
+
+if (it < 1) {
+    "lt one";
+  } else if (it + 1 === 1) {
+    "eq zero";
+  } else if (it === 2) {
+    "eq two";
+  } else if (f(it)) {
+    "f(x) truthy";
+  } else if (it.prop) {
+    "has prop";
+  } else if (it[0]) {
+    "has first child";
+  }

test/fixtures/match/basic-statement-call/actual.js

@@ -0,0 +1,7 @@
+match foo():
+  | 1:
+    "one"
+  | 2:
+    "two"
+  | else:
+    "idk"

test/fixtures/match/basic-statement-call/expected.js

@@ -0,0 +1,9 @@
+const it = foo();
+
+if (it === 1) {
+  "one";
+} else if (it === 2) {
+  "two";
+} else {
+  "idk";
+}