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[onechat] / view.go

diff --git a/view.go b/view.go
index 235719877517ad1cbce460dfa18ccb3c07af5366..9af1c21476fccfb2d1aa7ba394d8a3120ef2c35b 100644 (file)
--- a/view.go
+++ b/view.go
@@ -23,42 +23,6 @@ const (
        viewPending = "(not summarized yet: zoom it)"
 )
 
        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
 // 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
 }
 
        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{
 // 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 {
        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++
 
        }
 
        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
 }
 
 // Coarsen takes each merge of other, a view of the same messages, and then


@@ -206,6 +299,22 @@ func (v *View) LinesWithout(skip map[int]bool) []string {
        return lines
 }
 
        return lines
 }
 

+// renderLine writes one view line, "id+n|text", and a newline.
+func (v *View) renderLine(text *strings.Builder, line NodeKey) {
+       body := viewPending
+       node, built := v.nodes[line]
+       if built {
+               body = strings.ReplaceAll(node.Text, "\n", " ")
+       }
+
+       text.WriteString(strconv.Itoa(line.index << line.level))
+       text.WriteByte('+')
+       text.WriteString(strconv.Itoa(1 << line.level))
+       text.WriteByte('|')
+       text.WriteString(body)
+       text.WriteByte('\n')
+}
+

 // 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.
 // 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.


@@ -228,129 +337,29 @@ func (v *View) Context(end int) string {
        return text.String()
 }
 
        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
-       }
-
-       v.merging = false
-
-       return merged, nil
-}
-
-// renderLine writes one view line, "id+n|text", and a newline.
-func (v *View) renderLine(text *strings.Builder, line NodeKey) {
-       body := viewPending
-       node, built := v.nodes[line]
-       if built {
-               body = strings.ReplaceAll(node.Text, "\n", " ")
-       }
-
-       text.WriteString(strconv.Itoa(line.index << line.level))
-       text.WriteByte('+')
-       text.WriteString(strconv.Itoa(1 << line.level))
-       text.WriteByte('|')
-       text.WriteString(body)
-       text.WriteByte('\n')
-}
-
-// 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
+// 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 {
                if err != nil {

-                       return -1, fmt.Errorf("check parent node: %w", 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

 }
 }