From aaa26c3d7259319359565a77287a923c0822bba9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9C=80=E8=90=8C=E5=B0=8F=E6=B1=90?= <sumneko@hotmail.com>
Date: Fri, 22 Jan 2021 18:40:27 +0800
Subject: stash

---
 script/files.lua         |  34 ++++++++++++++--
 script/parser/guide.lua  |   2 +-
 script/string-merger.lua | 102 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 133 insertions(+), 5 deletions(-)
 create mode 100644 script/string-merger.lua

diff --git a/script/files.lua b/script/files.lua
index d5ff5981..679aa0cb 100644
--- a/script/files.lua
+++ b/script/files.lua
@@ -10,6 +10,7 @@ local timer    = require 'timer'
 local plugin   = require 'plugin'
 local util     = require 'utility'
 local guide    = require 'parser.guide'
+local smerger  = require 'string-merger'
 
 local m = {}
 
@@ -97,6 +98,34 @@ function m.asKey(uri)
     return uri
 end
 
+function m.setDiffInfo(uri, info)
+    uri = getUriKey(uri)
+    local file = m.fileMap[uri]
+    if not file then
+        return
+    end
+    file._diffInfo = info
+end
+
+local function pluginOnSetText(uri, text)
+    m.setDiffInfo(nil)
+    local suc, result = plugin.dispatch('OnSetText', uri, text)
+    if not suc then
+        return text
+    end
+    if type(result) == 'string' then
+        return result
+    elseif type(result) == 'table' then
+        local diffs
+        suc, result, diffs = xpcall(smerger.mergeDiff, log.warn, text, result)
+        if suc then
+            m.setDiffInfo(diffs)
+            return result
+        end
+    end
+    return text
+end
+
 --- 设置文件文本
 ---@param uri uri
 ---@param text string
@@ -116,10 +145,7 @@ function m.setText(uri, text)
         create = true
         m._pairsCache = nil
     end
-    local suc, newText = plugin.dispatch('OnSetText', originUri, text)
-    if not suc then
-        newText = text
-    end
+    local newText = pluginOnSetText(originUri, text)
     local file = m.fileMap[uri]
     if file.text == newText then
         return
diff --git a/script/parser/guide.lua b/script/parser/guide.lua
index 5f1bc230..5e4652b3 100644
--- a/script/parser/guide.lua
+++ b/script/parser/guide.lua
@@ -1370,7 +1370,7 @@ function m.getCallValue(source)
     end
     if call.node.special == 'pcall'
     or call.node.special == 'xpcall' then
-        return call.args[1], call.args, index - 1
+        return call.args and call.args[1], call.args, index - 1
     end
     return call.node, call.args, index
 end
diff --git a/script/string-merger.lua b/script/string-merger.lua
new file mode 100644
index 00000000..e6650f04
--- /dev/null
+++ b/script/string-merger.lua
@@ -0,0 +1,102 @@
+---@class string.merger.diff
+---@field start  integer # 替换开始的字节
+---@field finish integer # 替换结束的字节
+---@field text   string  # 替换的文本
+
+---@class string.merger.info: string.merger.diff
+---@field cstart  integer # 转换后的开始字节
+---@field cfinish integer # 转换后的结束字节
+
+---@alias string.merger.diffs string.merger.diff[]
+---@alias string.merger.infos string.merger.info[]
+
+-- 根据二分法找到最近的开始位置
+---@param diffs  table
+---@param offset any
+---@return string.merger.info
+local function getNearDiff(diffs, offset, key)
+    local min = 1
+    local max = #diffs
+    while max > min do
+        local middle = min + (max - min) // 2
+        local diff  = diffs[middle]
+        local ndiff = diffs[middle + 1]
+        if diff[key] > offset then
+            max = middle
+            goto CONTINUE
+        end
+        if not ndiff then
+            return diff
+        end
+        if ndiff[key] > offset then
+            return diff
+        end
+        if min == middle then
+            min = middle + 1
+        else
+            min = middle
+        end
+        ::CONTINUE::
+    end
+    return diffs[min]
+end
+
+local m = {}
+
+---把文本与差异进行合并
+---@param text  string
+---@param diffs string.merger.diffs
+---@return string
+---@return string.merger.infos
+function m.mergeDiff(text, diffs)
+    local info = {}
+    for i, diff in ipairs(diffs) do
+        info[i] = {
+            start  = diff.start,
+            finish = diff.finish,
+            text   = diff.text,
+        }
+    end
+    table.sort(info, function (a, b)
+        return a.start < b.start
+    end)
+    local cur = 1
+    local buf = {}
+    local delta = 0
+    for _, diff in ipairs(info) do
+        diff.cstart  = diff.start  + delta
+        diff.cfinish = diff.cstart + #diff.text - 1
+        buf[#buf+1] = text:sub(cur, diff.start - 1)
+        buf[#buf+1] = diff.text
+        cur = diff.finish + 1
+        delta = delta  + #diff.text - (diff.finish - diff.start + 1)
+    end
+    buf[#buf+1] = text:sub(cur)
+    return table.concat(buf), info
+end
+
+---根据转换前的位置获取转换后的位置
+---@param info   string.merger.infos
+---@param offset integer
+---@return integer
+function m.getOffset(info, offset)
+    local diff = getNearDiff(info, offset, 'start')
+    if offset <= diff.finish then
+        return diff.cstart
+    end
+    return offset - diff.finish + diff.cfinish
+end
+
+---根据转换后的位置获取转换前的位置
+---@param info   string.merger.infos
+---@param offset integer
+---@return integer
+function m.getOffsetBack(info, offset)
+    local diff = getNearDiff(info, offset, 'cstart')
+    if offset <= diff.cfinish then
+        return diff.start
+    end
+    return offset - diff.cfinish + diff.finish
+end
+
+return m
-- 
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