Add examples with formatted output

tshemsedinov · tshemsedinov · commit cecd741a5d30 · 2018-11-14T09:23:41.000+02:00
diff --git a/JavaScript/a-display.js b/JavaScript/a-display.js
@@ -0,0 +1,59 @@
+'use strict';
+
+// Projection
+
+const id = x => x;
+
+const projection = meta => src => meta.reduce(
+  (dest, [name, fn = id, field = name]) =>
+    (dest[name] = fn(src[field]), dest), {}
+);
+
+// Display
+
+const max = (a, b) => (a > b ? a : b);
+
+const render = meta => src => {
+  const keys = meta.map(([name]) => name);
+  const width = src.map(obj => keys.map(
+    key => obj[key].toString().length
+  ));
+  const maxWidth = keys.map(
+    (key, i) => width.reduce((a, b) => max(a, b[i]), 0)
+  );
+  const dest = src.map(obj => keys.map(
+    (key, i) => obj[key].toString().padEnd(maxWidth[i] + 4)
+  ));
+  return dest.map(row => row.join('')).join('\n');
+};
+
+// Dataset
+
+const persons = [
+  { name: 'Marcus Aurelius', city: 'Rome', born: 121 },
+  { name: 'Victor Glushkov', city: 'Rostov on Don', born: 1923 },
+  { name: 'Ibn Arabi', city: 'Murcia', born: 1165 },
+  { name: 'Mao Zedong', city: 'Shaoshan', born: 1893 },
+  { name: 'Rene Descartes', city: 'La Haye en Touraine', born: 1596 },
+];
+
+// Metadata
+
+const year = date => date.getFullYear();
+const diff = y => year(new Date()) - year(new Date(y + ''));
+const upper = s => s.toUpperCase();
+
+const md = [
+  ['name'],
+  ['place', upper, 'city'],
+  ['age', diff, 'born'],
+];
+
+// Usage
+
+const pf = projection(md);
+const data = persons.map(pf);
+
+const renderer = render(md);
+const res = renderer(data);
+console.log('\n' + res + '\n');
diff --git a/JavaScript/b-disp-opt.js b/JavaScript/b-disp-opt.js
@@ -0,0 +1,57 @@
+'use strict';
+
+// Projection
+
+const id = x => x;
+
+const projection = meta => src => meta.reduce(
+  (dest, [name, fn = id, field = name]) =>
+    (dest[name] = fn(src[field]), dest), {}
+);
+
+// Display
+
+const max = items => Math.max(...items);
+const maxProp = key => items => max(items.map(x => x[key]));
+const maxLength = maxProp('length');
+const col = (name, data) => data.map(obj => obj[name].toString());
+
+const render = meta => src => {
+  const keys = meta.map(([name]) => name);
+  const maxWidth = keys.map(key => maxLength(col(key, src)));
+  const dest = src.map(obj => maxWidth.map(
+    (width, i) => obj[keys[i]].toString().padEnd(width + 4)
+  ));
+  return dest.map(row => row.join('')).join('\n');
+};
+
+// Dataset
+
+const persons = [
+  { name: 'Marcus Aurelius', city: 'Rome', born: 121 },
+  { name: 'Victor Glushkov', city: 'Rostov on Don', born: 1923 },
+  { name: 'Ibn Arabi', city: 'Murcia', born: 1165 },
+  { name: 'Mao Zedong', city: 'Shaoshan', born: 1893 },
+  { name: 'Rene Descartes', city: 'La Haye en Touraine', born: 1596 },
+];
+
+// Metadata
+
+const year = date => date.getFullYear();
+const diff = y => year(new Date()) - year(new Date(y + ''));
+const upper = s => s.toUpperCase();
+
+const md = [
+  ['name'],
+  ['place', upper, 'city'],
+  ['age', diff, 'born'],
+];
+
+// Usage
+
+const pf = projection(md);
+const data = persons.map(pf);
+
+const renderer = render(md);
+const res = renderer(data);
+console.log('\n' + res + '\n');
