Add wasm bindings for predicates

lib/binding_web/test/query-test.js

@@ -19,7 +19,7 @@ describe("Query", () => {
   });
 
   describe('construction', () => {
-    it('throws an error on invalid syntax', () => {
+    it('throws an error on invalid patterns', () => {
       assert.throws(() => {
         JavaScript.query("(function_declaration wat)")
       }, "Bad syntax at offset 22: \'wat)\'...");
@@ -33,6 +33,24 @@ describe("Query", () => {
         JavaScript.query("(function_declaration non_existent:(identifier))")
       }, "Bad field name 'non_existent'");
     });
+
+    it('throws an error on invalid predicates',  () => {
+      assert.throws(() => {
+        JavaScript.query("((identifier) @abc (eq? @ab hi))")
+      }, "Bad capture name @ab");
+      assert.throws(() => {
+        JavaScript.query("((identifier) @abc (eq? @ab hi))")
+      }, "Bad capture name @ab");
+      assert.throws(() => {
+        JavaScript.query("((identifier) @abc (eq?))")
+      }, "Wrong number of arguments to `eq?` predicate. Expected 2, got 0");
+      assert.throws(() => {
+        JavaScript.query("((identifier) @a (eq? @a @a @a))")
+      }, "Wrong number of arguments to `eq?` predicate. Expected 2, got 3");
+      assert.throws(() => {
+        JavaScript.query("((identifier) @a (something-else? @a))")
+      }, "Unknown query predicate `something-else?`");
+    });
   });
 
   describe('.matches', () => {
@@ -119,6 +137,66 @@ describe("Query", () => {
         ]
       );
     });
+
+    it('handles conditions that compare the text of capture to literal strings',  () => {
+      tree = parser.parse(`
+        const ab = require('./ab');
+        new Cd(EF);
+      `);
+
+      query = JavaScript.query(`
+        (identifier) @variable
+
+        ((identifier) @function.builtin
+         (eq? @function.builtin "require"))
+
+        ((identifier) @constructor
+         (match? @constructor "^[A-Z]"))
+
+        ((identifier) @constant
+         (match? @constant "^[A-Z]{2,}$"))
+      `);
+
+      const captures = query.captures(tree.rootNode);
+      assert.deepEqual(
+        formatCaptures(captures),
+        [
+          {name: "variable", text: "ab"},
+          {name: "variable", text: "require"},
+          {name: "function.builtin", text: "require"},
+          {name: "variable", text: "Cd"},
+          {name: "constructor", text: "Cd"},
+          {name: "variable", text: "EF"},
+          {name: "constructor", text: "EF"},
+          {name: "constant", text: "EF"},
+        ]
+      );
+    });
+
+    it('handles conditions that compare the text of capture to each other',  () => {
+      tree = parser.parse(`
+        const ab = abc + 1;
+        const def = de + 1;
+        const ghi = ghi + 1;
+      `);
+
+      query = JavaScript.query(`
+        ((variable_declarator
+            name: (identifier) @id1
+            value: (binary_expression
+              left: (identifier) @id2))
+         (eq? @id1 @id2))
+      `);
+
+      const captures = query.captures(tree.rootNode);
+      assert.deepEqual(
+        formatCaptures(captures),
+        [
+          {name: "id1", text: "ghi"},
+          {name: "id2", text: "ghi"},
+        ]
+      );
+    });
   });
 });