Remove html-level indentation from src

vweb/src/undent.jsx

@@ -0,0 +1,45 @@
+// Remove an equal amount of leading whitespace from every line in a string,
+// such that some lines have zero leading whitespace. Also remove all trailing whitespace.
+export function undent(str) {
+    const isBlank = (ln) => ln.match(/^\s*$/)
+    const stripTrailingWs = ln => ln.match(/^(.*\S)\s*$/) // crashes on all-ws lines
+
+    const leadingWhitespaceCount = (ln) => {
+        const leadingWs = ln.match(/^(\s*)\S/)
+        return leadingWs ? leadingWs[1].length : 0
+    }
+
+    const setLeadingWhitespace = (ln, count) => {
+        const text = ln.match(/^\s*(\S.*)$/)[1]
+        return `${(' ').repeat(count)}${text}`
+    }
+
+    if (isBlank(str)) {
+        return ''
+    } // Degenerate case
+
+    const lines = str.split(/\n/)
+
+    if (lines.size === 1) { // Another degenerate case
+        return setLeadingWhitespace(stripTrailingWs(lines[0]), 0)
+    }
+
+    const leading = []
+    lines.forEach((line) => {
+        if (!isBlank(line)) {
+            leading.push(leadingWhitespaceCount(line))
+        }
+    })
+    const toRemove = Math.min(...leading)
+
+    const cleanLines = lines.map((line) => {
+        if (isBlank(line)) {
+            return ''
+        } else {
+            const current = leadingWhitespaceCount(line)
+            return setLeadingWhitespace(line, current - toRemove)
+        }
+    })
+
+    return cleanLines.join('\n')
+}