Allow escaping with $$

.github/workflows/ci.yml

@@ -34,8 +34,8 @@ jobs:
           git clone --depth 1 https://github.com/nvim-treesitter/nvim-treesitter.git ~/.local/share/nvim/site/pack/vendor/start/nvim-treesitter
           git clone --depth 1 https://github.com/nvim-lua/plenary.nvim ~/.local/share/nvim/site/pack/vendor/start/plenary.nvim
           ln -s $(pwd) ~/.local/share/nvim/site/pack/vendor/start
-          nvim --headless -c 'TSInstallSync python javascript lua rust go' -c 'q'
-          
+          nvim --headless -c 'TSInstallSync python javascript lua rust go bash' -c 'q'
+
       - name: Run tests
         run: |
           nvim --version

lua/ssr/parse.lua

@@ -3,6 +3,24 @@ local wildcard_prefix = require("ssr.search").wildcard_prefix
 
 local M = {}
 
+---Substituts $var using the provided function, and unescapes $$.
+---@param pattern string
+---@param replace fun(string):string a function that takes the variable name and returns the substitution result
+local function substitute_variables(pattern, replace)
+  return pattern:gsub("%$(%$?[_%a%d]*)", function(match)
+    if match == "" then
+      -- single $, not a valid variable
+      return "$"
+    end
+    if string.match(match, "^%$") then
+      -- this is an escaped $
+      return match
+    end
+
+    return replace(match)
+  end)
+end
+
 ---@class ParseContext
 ---@field lang string
 ---@field before string
@@ -68,7 +86,7 @@ end
 ---@return TSNode?, string
 function ParseContext:parse(pattern)
   -- Replace named wildcard $name to identifier __ssr_var_name to avoid syntax error.
-  pattern = pattern:gsub("%$([_%a%d]+)", wildcard_prefix .. "%1")
+  pattern = substitute_variables(pattern, function(var) return wildcard_prefix .. var end)
   local context_text = self.before .. pattern .. self.after
   local root = ts.get_string_parser(context_text, self.lang):parse()[1]:root()
   local lines = vim.split(pattern, "\n")

lua/ssr/search.lua

@@ -4,6 +4,24 @@ local u = require "ssr.utils"
 
 local M = {}
 
+---Substituts $var using the provided function, and unescapes $$.
+---@param pattern string
+---@param replace fun(integer, string):string a function that takes the position, variable name and returns the substitution result
+local function substitute_variables(pattern, replace)
+  return pattern:gsub("()%$(%$?[_%a%d]*)", function(pos, match)
+    if match == "" then
+      -- single $, not a valid variable
+      return "$"
+    end
+    if string.match(match, "^%$") then
+      -- this is an escaped $
+      return match
+    end
+
+    return replace(pos, match)
+  end)
+end
+
 M.wildcard_prefix = "__ssr_var_"
 
 ---@class Match
@@ -178,7 +196,7 @@ function M.search(buf, node, source, ns)
       return true
     end
     return (start_row1 > start_row2 or (start_row1 == start_row2 and start_col1 > start_col2))
-      and (end_row1 < end_row2 or (end_row1 == end_row2 and end_col1 <= end_col2))
+        and (end_row1 < end_row2 or (end_row1 == end_row2 and end_col1 <= end_col2))
   end)
 
   return matches
@@ -190,8 +208,12 @@ end
 ---@param template string
 function M.replace(buf, match, template)
   -- Render templates with captured nodes.
-  local replace = template:gsub("()%$([_%a%d]+)", function(pos, var)
-    local start_row, start_col, end_row, end_col = match.captures[var]:get()
+  local replace = substitute_variables(template, function(pos, var)
+    local capture = match.captures[var]
+    if capture == nil then
+      return "$" .. var
+    end
+    local start_row, start_col, end_row, end_col = capture:get()
     local lines = api.nvim_buf_get_text(buf, start_row, start_col, end_row, end_col, {})
     u.remove_indent(lines, u.get_indent(buf, start_row))
     local var_lines = vim.split(template:sub(1, pos), "\n")
@@ -200,6 +222,7 @@ function M.replace(buf, match, template)
     u.add_indent(lines, template_indent)
     return table.concat(lines, "\n")
   end)
+
   replace = vim.split(replace, "\n")
   local start_row, start_col, end_row, end_col = match.range:get()
   u.add_indent(replace, u.get_indent(buf, start_row))

tests/ssr_spec.lua

@@ -222,6 +222,22 @@ x
 local a = vim.api
 ]]
 
+t [[ bash escape dollar sign in pattern
+<$FOO=$$BAR>
+====
+$$FOO=$$$$BAR ==>> foo
+====
+foo
+]]
+
+t [[ bash escape dollar sign in template
+<${FOO:-bar}>
+====
+$${FOO:-$b} ==>> $b$$b$$$b
+====
+bar$b$bar
+]]
+
 describe("", function()
   -- Plenary runs nvim with `--noplugin` argument.
   -- Make sure nvim-treesitter is loaded, which populates vim.treesitter's ft_to_lang table.