SELECT

Author: Snowflake107

src/util/methods/select.js

@@ -8,11 +8,74 @@ module.exports = (ast, db) => {
     const data = db.db[table];
     if (!data) throw new Error(`Table \"${table}\" does not exist`);
 
-    const fn = chunk(
-        data.data.map((m) => ({ key: m.key, data: m.data ?? null })),
-        2
-    );
-
-    if (limit >= 0) return fn.slice(0, limit);
-    return fn;
+    if (!ast.where) {
+        const fn = chunk(
+            data.data.map((m) => ({ key: m.key, data: m.data ?? null })),
+            2
+        );
+        if (limit >= 0) return handle(fn.slice(0, limit));
+        return handle(fn);
+    } else {
+        const bin = binOp(data, { op: ast.where.operator, left: ast.where.left.value, right: ast.where.right.value });
+        if (limit >= 0) return handle(bin.data?.slice(0, limit) ?? []);
+        return handle(bin.data ?? []);
+    }
 };
+
+function handle(d) {
+    if (!d) return [];
+
+    return Object.defineProperties(d, {
+        parse: {
+            value: () => {
+                return d.map(col => {
+                    let obj = {};
+
+                    col.forEach(keys => {
+                        obj[keys.key] = keys.data;
+                    });
+
+                    return obj;
+                })
+            }
+        },
+    });
+}
+
+function binOp(data, clause) {
+    switch (clause.op) {
+        case '=': {
+            const dat = [];
+            const child = chunk(data.data, 2);
+            for (let i = 0; i < child.length; i++) {
+                if (child[i].some(m => m.key === clause.left && m.data === clause.right)) dat.push(child[i]);
+            }
+
+            try {
+                return {
+                    data: dat
+                };
+            } catch {
+                throw new Error(`Could not verify operation "${clause.left} = ${clause.right}"`);
+            }
+        }
+
+        case 'IS NOT': {
+            const dat = [];
+            const child = chunk(data.data, 2);
+            for (let i = 0; i < child.length; i++) {
+                if (child[i].some(m => m.key === clause.left && m.data !== clause.right)) dat.push([child[i]]);
+            }
+
+            try {
+                return {
+                    data: dat
+                };
+            } catch {
+                throw new Error(`Could not verify operation "${clause.left} = ${clause.right}"`);
+            }
+        }
+        default:
+            return { data: [] };
+    }
+}