-- Copyright 2026 Open-Guji (https://github.com/open-guji) -- -- Licensed under the Apache License, Version 2.0 (the "License"); -- you may not use this file except in compliance with the License. -- You may obtain a copy of the License at -- -- http://www.apache.org/licenses/LICENSE-2.0 -- -- Unless required by applicable law or agreed to in writing, software -- distributed under the License is distributed on an "AS IS" BASIS, -- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -- See the License for the specific language governing permissions and -- limitations under the License. -- ============================================================================ -- flatten_nodes.lua - 盒子展平与缩进提取（第一阶段） -- ============================================================================ -- 文件名: flatten_nodes.lua (原 flatten.lua) -- 层级: 第一阶段 - 展平层 (Stage 1: Flatten Layer) -- -- 【模块功能 / Module Purpose】 -- 本模块负责排版流水线的第一阶段，将 TeX 复杂的嵌套盒子结构转化为一维节点流： -- 1. 递归遍历 VBox/HBox，将多层嵌套展平为线性节点列表 -- 2. 自动检测并提取缩进信息（leftskip glue、box shift） -- 3. 将缩进值转换为字符数并附加为节点属性（ATTR_INDENT） -- 4. 在适当位置插入列中断标记（penalty -10001） -- 5. 过滤无用节点（保留 glyph、kern、特定 glue、textbox 块） -- -- 【术语对照 / Terminology】 -- flatten - 展平（将嵌套结构转为线性结构） -- indent - 缩进（首行或悬挂缩进） -- leftskip - 左侧跳过（TeX 的段落左缩进机制） -- shift - 盒子偏移（box.shift 属性） -- penalty - 惩罚值（用于控制换行/换列） -- column break - 列中断（-10001 触发强制换列） -- running_indent - 当前累积缩进（随遍历更新） -- has_content - 是否有可见内容（字形或文本框） -- -- 【注意事项】 -- • 缩进检测依赖 TeX 的 \leftskip 和 box.shift 机制，支持标准的 itemize/enumerate -- • "列中断"（penalty -10001）在每个 HLIST 行之后插入，用于 layout_grid.lua 识别强制换列 -- • 重点：展平算法高度依赖 TeX 的段落构建，若节点在垂直模式输出（如列表开头的 Textbox）， -- 其缩进属性（leftskip）将无法被检测。因此 TeX 端必须确保进入水平模式（如使用 \leavevmode） -- • Textbox 块通过属性 ATTR_TEXTBOX_WIDTH/HEIGHT 识别，会被完整保留 -- • 右缩进（rightskip）功能已预留但未完全实现（当前只在 layout 中使用） -- • 节点会被复制（D.copy），原始盒子不会被修改 -- -- 【整体架构 / Architecture】 -- 输入: TeX VBox.list (嵌套的 vlist/hlist/glyph 树) -- ↓ -- flatten_vbox(head, grid_width, char_width) -- ├─ collect_nodes() 递归遍历 -- │ ├─ 检测 leftskip → 更新 indent -- │ ├─ 检测 shift → 更新 indent -- │ └─ 递归处理子盒子 -- ├─ 为每个节点附加 ATTR_INDENT 属性 -- └─ 在行尾插入 penalty -10001 -- ↓ -- 输出: 一维节点流（glyph + kern + glue + penalty + textbox块） -- -- ============================================================================ -- Load dependencies -- Check if already loaded via dofile (package.loaded set manually) local constants = package.loaded['core.luatex-cn-constants'] or require('core.luatex-cn-constants') local D = constants.D local utils = package.loaded['util.luatex-cn-utils'] or require('util.luatex-cn-utils') local debug = package.loaded['debug.luatex-cn-debug'] or require('debug.luatex-cn-debug') local dbg = debug.get_debugger('flatten') local _internal = {} --- 计算盒子的缩进（基于 shift 和 leftskip） -- @param box (direct node) HLIST 或 VLIST 节点 -- @param current_indent (number) 当前累积的缩进值 -- @param char_width (number) 字符宽度 -- @return (number) 新的缩进值 local function get_box_indentation(box, current_indent, char_width) local box_indent = current_indent local tid = D.getid(box) -- Detect Shift on any box local shift = D.getfield(box, "shift") or 0 if shift > 0 then box_indent = math.max(box_indent, math.floor(shift / char_width + 0.5)) end -- Priority 2: Check for direct attribute on the box (set by \Paragraph environment) local attr_indent = D.get_attribute(box, constants.ATTR_INDENT) or 0 if attr_indent > 0 then box_indent = math.max(box_indent, attr_indent) end if tid == constants.HLIST then -- Check for indent glue/kern inside HLIST local s = D.getfield(box, "list") while s do local sid = D.getid(s) if sid == constants.GLYPH or sid == constants.WHATSIT then break end if sid == constants.GLUE or sid == constants.KERN then local w = D.getfield(s, "width") or 0 if w > 0 then local calc = w / char_width box_indent = math.max(box_indent, math.floor(calc + 0.5)) end end s = D.getnext(s) end end return box_indent end --- 判断是否保留该节点 -- @param tid (number) 节点 ID -- @param subtype (number) 节点子类型 -- @return (boolean) 是否保留 local function should_keep_node(tid, subtype) if tid == constants.GLYPH or tid == constants.KERN then return true elseif tid == constants.GLUE or tid == constants.WHATSIT then -- Keep typical glues (0), spaces (13, 14), and WHATITS if tid == constants.WHATSIT or subtype == 0 or subtype == 13 or subtype == 14 then return true end elseif tid == constants.PENALTY then return true end return false end _internal.get_box_indentation = get_box_indentation --- 复制节点并应用属性 -- @param t (direct node) 源节点 -- @param indent (number) 缩进值 -- @param r_indent (number) 右缩进值 -- @return (direct node) 复制后的节点 local function copy_node_with_attributes(t, indent, r_indent) local copy = D.copy(t) local tid = D.getid(t) if tid == constants.PENALTY then -- Penalty nodes don't occupy layout space — clear any inherited -- indent attributes to prevent Column boundary markers from causing -- layout grid to create empty columns. -- Use set_attribute with 0 since unset_attribute may not be available -- in all LuaTeX versions and 0 means "no indent" in resolve_node_indent. D.set_attribute(copy, constants.ATTR_INDENT, 0) D.set_attribute(copy, constants.ATTR_FIRST_INDENT, 0) else if indent > 0 then -- Don't overwrite command-level indent values on individual nodes -- (e.g., \缩进 or \抬头 set via tex.setattribute with encode_suojin/taitou_indent) local existing = D.get_attribute(copy, constants.ATTR_INDENT) or 0 if not constants.is_any_command_indent(existing) then D.set_attribute(copy, constants.ATTR_INDENT, indent) end end if r_indent > 0 then D.set_attribute(copy, constants.ATTR_RIGHT_INDENT, r_indent) end end -- CRITICAL: Preserve textflow attributes (they are set by \TextFlow command) local textflow_attr = D.get_attribute(t, constants.ATTR_JIAZHU) if textflow_attr then D.set_attribute(copy, constants.ATTR_JIAZHU, textflow_attr) end local textflow_sub_attr = D.get_attribute(t, constants.ATTR_JIAZHU_SUB) if textflow_sub_attr then D.set_attribute(copy, constants.ATTR_JIAZHU_SUB, textflow_sub_attr) end local textflow_mode_attr = D.get_attribute(t, constants.ATTR_JIAZHU_MODE) if textflow_mode_attr then D.set_attribute(copy, constants.ATTR_JIAZHU_MODE, textflow_mode_attr) end -- CRITICAL: Preserve block indentation attributes local block_id = D.get_attribute(t, constants.ATTR_BLOCK_ID) if block_id then D.set_attribute(copy, constants.ATTR_BLOCK_ID, block_id) end local first_indent = D.get_attribute(t, constants.ATTR_FIRST_INDENT) if first_indent then D.set_attribute(copy, constants.ATTR_FIRST_INDENT, first_indent) end return copy end --- 处理 Textbox 节点 local function process_textbox_node(t, running_indent, running_r_indent) local tb_w = D.get_attribute(t, constants.ATTR_TEXTBOX_WIDTH) or 0 local tb_h = D.get_attribute(t, constants.ATTR_TEXTBOX_HEIGHT) or 0 if tb_w > 0 and tb_h > 0 then local copy = D.copy(t) -- Apply running indent (inherited from previous lines if needed) if running_indent > 0 then D.set_attribute(copy, constants.ATTR_INDENT, running_indent) end if running_r_indent > 0 then D.set_attribute(copy, constants.ATTR_RIGHT_INDENT, running_r_indent) end -- Preserve block indentation attributes local block_id = D.get_attribute(t, constants.ATTR_BLOCK_ID) if block_id then D.set_attribute(copy, constants.ATTR_BLOCK_ID, block_id) end local first_indent = D.get_attribute(t, constants.ATTR_FIRST_INDENT) if first_indent then D.set_attribute(copy, constants.ATTR_FIRST_INDENT, first_indent) end return copy, true end return nil, false end _internal.copy_node_with_attributes = copy_node_with_attributes _internal.process_textbox_node = process_textbox_node --- 将 vlist（来自 vbox）展平为单一节点列表 -- 从行首提取缩进并将其应用为属性。 -- 同时清理节点（保留有效的胶水/字形）。 -- -- @param head (node) vlist 的头部 -- @param grid_width (number) 以 SCALED POINTS 为单位网格列宽 -- @param char_width (number) 用于缩进计算的字符宽度（通常为 grid_height） -- @return (node) 带有缩进属性的展平节点列表 local function flatten_vbox(head, grid_width, char_width) local d_head = D.todirect(head) local result_head_d = nil local result_tail_d = nil --- 向结果列表追加一个节点 -- @param n (direct node) 要追加的节点 local function append_node(n) if not n then return end D.setnext(n, nil) if not result_head_d then result_head_d = n result_tail_d = n else D.setlink(result_tail_d, n) result_tail_d = n end end --- 递归节点收集器 -- @param n_head (direct node) 要收集的节点列表头部（将被消耗） -- @param indent_lvl (number) 当前缩进 -- @param r_indent_lvl (number) 当前右缩进 -- @param parent_is_vlist (boolean) 父节点是否为 VLIST（用于判断是否为行盒子） -- @return (boolean) 如果收集到了任何可见内容（字形/文本框），则返回 true local function collect_nodes(n_head, indent_lvl, r_indent_lvl, parent_is_vlist) local t = n_head local running_indent = indent_lvl local running_r_indent = r_indent_lvl local has_content = false while t do local tid = D.getid(t) local subtype = D.getsubtype(t) -- 1. Try to process as Textbox Block local tb_node, is_tb = process_textbox_node(t, running_indent, running_r_indent) if is_tb then append_node(tb_node) has_content = true elseif tid == constants.HLIST or tid == constants.VLIST then -- 2. Process recursable box (HList/VList) local inner = D.getfield(t, "list") -- Calculate indentation for this box local box_indent = get_box_indentation(t, running_indent, char_width) local box_r_indent = running_r_indent -- Right indent logic propagation (if needed) -- Recurse -- If current node is VLIST, its children are in vertical flow. -- If current node is HLIST, its children are inline. local inner_parent_is_vlist = (tid == constants.VLIST) local inner_has_content = collect_nodes(inner, box_indent, box_r_indent, inner_parent_is_vlist) if inner_has_content then has_content = true end -- IMPORTANT: Only add penalty for HLIST lines that are part of -- the main vertical flow. This prevents inline HLISTs (like \box0 in decorate) -- from triggering unwanted column breaks. -- Skip adding penalty if: -- 1. The last appended node is already a PENALTY_FORCE_COLUMN, or -- 2. The next sibling in the VLIST is a PENALTY_FORCE_COLUMN -- (e.g., from \penalty -10002 in footnote content that caused a -- paragraph line break; TeX places this penalty between HLISTs) if tid == constants.HLIST and inner_has_content and parent_is_vlist then local last_penalty = result_tail_d and D.getid(result_tail_d) == constants.PENALTY and D.getfield(result_tail_d, "penalty") local already_has_penalty = last_penalty == constants.PENALTY_FORCE_COLUMN or last_penalty == constants.PENALTY_TAITOU or last_penalty == constants.PENALTY_DIGITAL_NEWLINE local next_sibling = D.getnext(t) local next_penalty = next_sibling and D.getid(next_sibling) == constants.PENALTY and D.getfield(next_sibling, "penalty") local next_is_force_column = next_penalty == constants.PENALTY_FORCE_COLUMN or next_penalty == constants.PENALTY_TAITOU or next_penalty == constants.PENALTY_DIGITAL_NEWLINE if not already_has_penalty and not next_is_force_column then dbg.log("Adding Column Break after Line=" .. tostring(t)) local p = D.new(constants.PENALTY) D.setfield(p, "penalty", -10002) append_node(p) end end else -- 3. Process leaf nodes if should_keep_node(tid, subtype) then local copy = copy_node_with_attributes(t, running_indent, running_r_indent) D.set_attribute(copy, constants.ATTR_TEXTBOX_WIDTH, 0) D.set_attribute(copy, constants.ATTR_TEXTBOX_HEIGHT, 0) append_node(copy) if tid == constants.GLYPH or tid == constants.WHATSIT then has_content = true end end end t = D.getnext(t) end return has_content end -- Initial call: treat input as VList content (true) collect_nodes(d_head, 0, 0, true) return D.tonode(result_head_d) end -- Create module table local flatten = { flatten_vbox = flatten_vbox, _internal = _internal, } -- Register module in package.loaded for require() compatibility -- 注册模块到 package.loaded package.loaded['core.luatex-cn-core-flatten-nodes'] = flatten -- Return module exports return flatten