X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/4a931bccab5879ab708647b2df8dadc052f128bf..98d137c3e945a09f76e85bd18238558c668fdca4:/view.go?ds=sidebyside

diff --git a/view.go b/view.go
index 233e089..9af1c21 100644
--- a/view.go
+++ b/view.go
@@ -23,42 +23,6 @@ const (
 	viewPending = "(not summarized yet: zoom it)"
 )
 
-// newView returns an empty view with the limits high and low.
-func newView(high, low int) *View {
-	return &View{
-		high:  high,
-		low:   low,
-		nodes: make(map[NodeKey]Node),
-	}
-}
-
-// restoreView returns the view of state with the limits high and low. Each line
-// must continue the one before it, and each line above level 0 must be built.
-func restoreView(state ViewState, high, low int, tree ViewNodeReader) (*View, error) {
-	v := newView(high, low)
-	v.merging = state.Merging
-	for _, pair := range state.Lines {
-		line := NodeKey{pair[0], pair[1]}
-		if line.level < 0 || line.level >= bits.UintSize-2 || line.index < 0 || line.index<<line.level != v.end {
-			return nil, fmt.Errorf("view line (%d, %d) does not start at message %d", line.level, line.index, v.end)
-		}
-
-		built, err := v.load(tree, line)
-		if err != nil {
-			return nil, err
-		}
-
-		if line.level > 0 && !built {
-			return nil, fmt.Errorf("view line (%d, %d) is not built", line.level, line.index)
-		}
-
-		v.lines = append(v.lines, line)
-		v.end = nodeEnd(line.level, line.index)
-	}
-
-	return v, nil
-}
-
 // View is a list of tree nodes that covers messages 0 to end-1 without a gap,
 // oldest first. Each new message appends its leaf as a line. Once the size of
 // the view goes above high, one batch merges the most due sibling pairs until
@@ -83,6 +47,27 @@ type View struct {
 	merging bool
 }
 
+// ViewState is the saved form of a View. The limits are not part of it.
+type ViewState struct {
+	Lines   [][2]int `json:"lines"`
+	Merging bool     `json:"merging"`
+}
+
+// ViewNodeReader gives the built nodes of a tree.
+type ViewNodeReader interface {
+	Built(level, index int) (bool, error)
+	Node(level, index int) (Node, bool, error)
+}
+
+// newView returns an empty view with the limits high and low.
+func newView(high, low int) *View {
+	return &View{
+		high:  high,
+		low:   low,
+		nodes: make(map[NodeKey]Node),
+	}
+}
+
 // State returns the saved form of the view.
 func (v *View) State() ViewState {
 	state := ViewState{
@@ -103,13 +88,121 @@ func (v *View) Append(tree ViewNodeReader) (bool, error) {
 	line := NodeKey{0, v.end}
 	_, err := v.load(tree, line)
 	if err != nil {
-		return false, err
+		return false, fmt.Errorf("load appended leaf: %w", err)
 	}
 
 	v.lines = append(v.lines, line)
 	v.end++
 
-	return v.fit(tree)
+	merged, err := v.fit(tree)
+	if err != nil {
+		return merged, fmt.Errorf("fit appended view: %w", err)
+	}
+
+	return merged, nil
+}
+
+// load keeps the node of line when it is built, and tells if it is.
+func (v *View) load(tree ViewNodeReader, line NodeKey) (bool, error) {
+	node, built, err := tree.Node(line.level, line.index)
+	if err != nil || !built {
+		return false, err
+	}
+
+	v.nodes[line] = node
+
+	return true, nil
+}
+
+// fit merges the most due pairs while a batch runs, and tells if a merge
+// changed the view.
+func (v *View) fit(tree ViewNodeReader) (bool, error) {
+	size := v.Size()
+	if size > v.high {
+		v.merging = true
+	}
+
+	merged := false
+	for v.merging && size > v.low {
+		best, err := v.mostDue(tree)
+		if err != nil || best < 0 {
+			if err != nil {
+				return merged, fmt.Errorf("choose merge candidate: %w", err)
+			}
+
+			return merged, nil
+		}
+
+		left, right := v.lines[best], v.lines[best+1]
+		parent := NodeKey{left.level + 1, left.index / 2}
+		_, err = v.load(tree, parent)
+		if err != nil {
+			return merged, fmt.Errorf("load merged parent: %w", err)
+		}
+
+		size += v.lineSize(parent) - v.lineSize(left) - v.lineSize(right)
+		delete(v.nodes, left)
+		delete(v.nodes, right)
+
+		v.lines[best] = parent
+		v.lines = append(v.lines[:best+1], v.lines[best+2:]...)
+		merged = true
+	}
+
+	v.merging = false
+
+	return merged, nil
+}
+
+// Size returns the sum of the line sizes.
+func (v *View) Size() int {
+	size := 0
+	for _, line := range v.lines {
+		size += v.lineSize(line)
+	}
+
+	return size
+}
+
+// mostDue returns the position of the left line of the most due sibling pair
+// whose parent is built, or -1 when there is no such pair.
+func (v *View) mostDue(tree ViewNodeReader) (int, error) {
+	best := -1
+	bestDue := 0.0
+	for n := 0; n+1 < len(v.lines); n++ {
+		left, right := v.lines[n], v.lines[n+1]
+		if left.index%2 != 0 || right.level != left.level || right.index != left.index+1 {
+			continue
+		}
+
+		last := nodeEnd(right.level, right.index) - 1
+		due := math.Ldexp(float64(v.end-last), -left.level)
+		if best >= 0 && due <= bestDue {
+			continue
+		}
+
+		built, err := tree.Built(left.level+1, left.index/2)
+		if err != nil {
+			return -1, fmt.Errorf("check parent node: %w", err)
+		}
+
+		if built {
+			best = n
+			bestDue = due
+		}
+	}
+
+	return best, nil
+}
+
+// lineSize returns the size of a view line.
+func (v *View) lineSize(line NodeKey) int {
+	node, built := v.nodes[line]
+	if !built {
+		return len(viewPending)
+	}
+
+	return node.Size
 }
 
 // Coarsen takes each merge of other, a view of the same messages, and then
@@ -197,78 +290,13 @@ func (v *View) LinesWithout(skip map[int]bool) []string {
 		}
 
 		var text strings.Builder
-		v.renderLine(&text, line)
-		lines = append(lines, text.String())
-	}
-
-	return lines
-}
-
-// Context returns the lines of the view before message end as the model reads
-// them. It stops at the first line that is not built, so a compaction never
-// sees a pending mark or a part of a message.
-func (v *View) Context(end int) string {
-	var text strings.Builder
-	text.WriteString("<chat>\n")
-	for _, line := range v.lines {
-		_, built := v.nodes[line]
-		if !built || nodeEnd(line.level, line.index) > end {
-			break
-		}
 
 		v.renderLine(&text, line)
-	}
-
-	text.WriteString("</chat>")
-
-	return text.String()
-}
-
-// load keeps the node of line when it is built, and tells if it is.
-func (v *View) load(tree ViewNodeReader, line NodeKey) (bool, error) {
-	node, built, err := tree.Node(line.level, line.index)
-	if err != nil || !built {
-		return false, err
-	}
-
-	v.nodes[line] = node
-
-	return true, nil
-}
-
-// fit merges the most due pairs while a batch runs, and tells if a merge
-// changed the view.
-func (v *View) fit(tree ViewNodeReader) (bool, error) {
-	size := v.Size()
-	if size > v.high {
-		v.merging = true
-	}
-
-	merged := false
-	for v.merging && size > v.low {
-		best, err := v.mostDue(tree)
-		if err != nil || best < 0 {
-			return merged, err
-		}
-
-		left, right := v.lines[best], v.lines[best+1]
-		parent := NodeKey{left.level + 1, left.index / 2}
-		_, err = v.load(tree, parent)
-		if err != nil {
-			return merged, err
-		}
 
-		size += v.lineSize(parent) - v.lineSize(left) - v.lineSize(right)
-		delete(v.nodes, left)
-		delete(v.nodes, right)
-		v.lines[best] = parent
-		v.lines = append(v.lines[:best+1], v.lines[best+2:]...)
-		merged = true
+		lines = append(lines, text.String())
 	}
 
-	v.merging = false
-
-	return merged, nil
+	return lines
 }
 
 // renderLine writes one view line, "id+n|text", and a newline.
@@ -287,65 +315,51 @@ func (v *View) renderLine(text *strings.Builder, line NodeKey) {
 	text.WriteByte('\n')
 }
 
-// Size returns the sum of the line sizes.
-func (v *View) Size() int {
-	size := 0
+// Context returns the lines of the view before message end as the model reads
+// them. It stops at the first line that is not built, so a compaction never
+// sees a pending mark or a part of a message.
+func (v *View) Context(end int) string {
+	var text strings.Builder
+
+	text.WriteString("<chat>\n")
+
 	for _, line := range v.lines {
-		size += v.lineSize(line)
+		_, built := v.nodes[line]
+		if !built || nodeEnd(line.level, line.index) > end {
+			break
+		}
+
+		v.renderLine(&text, line)
 	}
 
-	return size
-}
+	text.WriteString("</chat>")
 
-// mostDue returns the position of the left line of the most due sibling pair
-// whose parent is built, or -1 when there is no such pair.
-func (v *View) mostDue(tree ViewNodeReader) (int, error) {
-	best := -1
-	bestDue := 0.0
-	for n := 0; n+1 < len(v.lines); n++ {
-		left, right := v.lines[n], v.lines[n+1]
-		if left.index%2 != 0 || right.level != left.level || right.index != left.index+1 {
-			continue
-		}
+	return text.String()
+}
 
-		last := nodeEnd(right.level, right.index) - 1
-		due := math.Ldexp(float64(v.end-last), -left.level)
-		if best >= 0 && due <= bestDue {
-			continue
+// restoreView returns the view of state with the limits high and low. Each line
+// must continue the one before it, and each line above level 0 must be built.
+func restoreView(state ViewState, high, low int, tree ViewNodeReader) (*View, error) {
+	v := newView(high, low)
+	v.merging = state.Merging
+	for _, pair := range state.Lines {
+		line := NodeKey{pair[0], pair[1]}
+		if line.level < 0 || line.level >= bits.UintSize-2 || line.index < 0 || line.index<<line.level != v.end {
+			return nil, fmt.Errorf("view line (%d, %d) does not start at message %d", line.level, line.index, v.end)
 		}
 
-		built, err := tree.Built(left.level+1, left.index/2)
+		built, err := v.load(tree, line)
 		if err != nil {
-			return -1, err
+			return nil, fmt.Errorf("load restored view node: %w", err)
 		}
 
-		if built {
-			best = n
-			bestDue = due
+		if line.level > 0 && !built {
+			return nil, fmt.Errorf("view line (%d, %d) is not built", line.level, line.index)
 		}
-	}
 
-	return best, nil
-}
-
-// lineSize returns the size of a view line.
-func (v *View) lineSize(line NodeKey) int {
-	node, built := v.nodes[line]
-	if !built {
-		return len(viewPending)
+		v.lines = append(v.lines, line)
+		v.end = nodeEnd(line.level, line.index)
 	}
 
-	return node.Size
-}
-
-// ViewState is the saved form of a View. The limits are not part of it.
-type ViewState struct {
-	Lines   [][2]int `json:"lines"`
-	Merging bool     `json:"merging"`
-}
-
-// ViewNodeReader gives the built nodes of a tree.
-type ViewNodeReader interface {
-	Built(level, index int) (bool, error)
-	Node(level, index int) (Node, bool, error)
+	return v, nil
 }