refactor(format): subqueries and CTE lists on Doc-IR; fix CTE commas with trailing style

pkg/format/doc.go

@@ -13,7 +13,7 @@ type Doc interface{ isDoc() }
 
 type (
 	docText   string
-	docLine   struct{ soft bool }
+	docLine   struct{ soft, hard bool }
 	docConcat []Doc
 	docIndent struct{ d Doc }
 	docGroup  struct{ d Doc }
@@ -37,6 +37,24 @@ func Line() Doc { return docLine{} }
 // SoftLine is nothing when flat and a newline (plus indentation) when broken.
 func SoftLine() Doc { return docLine{soft: true} }
 
+// HardLine is always a newline (plus indentation), even inside a flat group; a
+// group containing one can never be printed flat.
+func HardLine() Doc { return docLine{hard: true} }
+
+// Lines turns multi-line text into Text pieces joined by HardLines so that each
+// line picks up the surrounding Indent. Empty lines carry no indentation.
+func Lines(s, nl string) Doc {
+	parts := strings.Split(s, nl)
+	ds := make([]Doc, 0, 2*len(parts))
+	for i, p := range parts {
+		if i > 0 {
+			ds = append(ds, HardLine())
+		}
+		ds = append(ds, Text(p))
+	}
+	return Concat(ds...)
+}
+
 // Concat joins docs in order.
 func Concat(ds ...Doc) Doc { return docConcat(ds) }
 
@@ -59,12 +77,17 @@ type docCmd struct {
 func Render(d Doc, width int, unit, nl string) string {
 	var b strings.Builder
 	col := 0
+	pending := "" // indentation owed to the next non-empty text
 	stack := []docCmd{{"", false, d}}
 	for len(stack) > 0 {
 		c := stack[len(stack)-1]
 		stack = stack[:len(stack)-1]
 		switch v := c.d.(type) {
 		case docText:
+			if len(v) > 0 {
+				b.WriteString(pending)
+				pending = ""
+			}
 			b.WriteString(string(v))
 			if i := strings.LastIndexByte(string(v), '\n'); i >= 0 {
 				col = len(v) - i - 1
@@ -84,7 +107,7 @@ func Render(d Doc, width int, unit, nl string) string {
 				stack = append(stack, docCmd{c.indent, c.flat, v.broken})
 			}
 		case docLine:
-			if c.flat {
+			if c.flat && !v.hard {
 				if !v.soft {
 					b.WriteByte(' ')
 					col++
@@ -92,7 +115,7 @@ func Render(d Doc, width int, unit, nl string) string {
 				break
 			}
 			b.WriteString(nl)
-			b.WriteString(c.indent)
+			pending = c.indent
 			col = len(c.indent)
 		case docGroup:
 			flat := c.flat || width <= 0 || fitsFlat(v.d, width-col, c.indent, unit, stack)
@@ -146,6 +169,9 @@ func fitsFlat(d Doc, rem int, indent, unit string, rest []docCmd) bool {
 				work = append(work, item{v.broken, it.flat})
 			}
 		case docLine:
+			if v.hard {
+				return false
+			}
 			if !it.flat {
 				return true // a real line break ends the measured run
 			}