223 lines
7.7 KiB
Lua
223 lines
7.7 KiB
Lua
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-- LuaInspect.globals - identifier scope analysis
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-- Locates locals, globals, and their definitions.
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--
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-- (c) D.Manura, 2008-2010, MIT license.
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-- based on http://lua-users.org/wiki/DetectingUndefinedVariables
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local M = {}
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--! require 'luainspect.typecheck' (context)
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local LA = require "luainspect.ast"
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local function definelocal(scope, name, ast)
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if scope[name] then
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scope[name].localmasked = true
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ast.localmasking = scope[name]
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end
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scope[name] = ast
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if name == '_' then ast.isignore = true end
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end
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-- Resolves scoping and usages of variable in AST.
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-- Data Notes:
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-- ast.localdefinition refers to lexically scoped definition of `Id node `ast`.
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-- If ast.localdefinition == ast then ast is a "lexical definition".
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-- If ast.localdefinition == nil, then variable is global.
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-- ast.functionlevel is the number of functions the AST is contained in.
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-- ast.functionlevel is defined iff ast is a lexical definition.
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-- ast.isparam is true iff ast is a lexical definition and a function parameter.
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-- ast.isset is true iff ast is a lexical definition and exists an assignment on it.
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-- ast.isused is true iff ast is a lexical definition and has been referred to.
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-- ast.isignore is true if local variable should be ignored (e.g. typically "_")
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-- ast.localmasking - for a lexical definition, this is set to the lexical definition
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-- this is masking (i.e. same name). nil if not masking.
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-- ast.localmasked - true iff lexical definition masked by another lexical definition.
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-- ast.isfield is true iff `String node ast is used for field access on object,
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-- e.g. x.y or x['y'].z
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-- ast.previous - For `Index{o,s} or `Invoke{o,s,...}, s.previous == o
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local function traverse(ast, scope, globals, level, functionlevel)
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scope = scope or {}
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local blockrecurse
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ast.level = level
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-- operations on walking down the AST
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if ast.tag == 'Local' then
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blockrecurse = 1
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-- note: apply new scope after processing values
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elseif ast.tag == 'Localrec' then
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local namelist_ast, valuelist_ast = ast[1], ast[2]
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for _,value_ast in ipairs(namelist_ast) do
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assert(value_ast.tag == 'Id')
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local name = value_ast[1]
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local parentscope = getmetatable(scope).__index
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definelocal(parentscope, name, value_ast)
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value_ast.localdefinition = value_ast
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value_ast.functionlevel = functionlevel
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value_ast.level = level+1
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end
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blockrecurse = 1
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elseif ast.tag == 'Id' then
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local name = ast[1]
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if scope[name] then
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ast.localdefinition = scope[name]
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ast.functionlevel = functionlevel
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scope[name].isused = true
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else -- global, do nothing
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end
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elseif ast.tag == 'Function' then
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local paramlist_ast, body_ast = ast[1], ast[2]
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functionlevel = functionlevel + 1
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for _,param_ast in ipairs(paramlist_ast) do
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local name = param_ast[1]
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assert(param_ast.tag == 'Id' or param_ast.tag == 'Dots')
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if param_ast.tag == 'Id' then
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definelocal(scope, name, param_ast)
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param_ast.localdefinition = param_ast
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param_ast.functionlevel = functionlevel
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param_ast.isparam = true
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end
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param_ast.level = level+1
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end
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blockrecurse = 1
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elseif ast.tag == 'Set' then
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local reflist_ast, valuelist_ast = ast[1], ast[2]
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for _,ref_ast in ipairs(reflist_ast) do
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if ref_ast.tag == 'Id' then
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local name = ref_ast[1]
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if scope[name] then
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scope[name].isset = true
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else
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if not globals[name] then
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globals[name] = {set=ref_ast}
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end
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end
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end
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ref_ast.level = level+1
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end
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--ENHANCE? We could differentiate assignments to x (which indicates that
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-- x is not const) and assignments to a member of x (which indicates that
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-- x is not a pointer to const) and assignments to any nested member of x
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-- (which indicates that x it not a transitive const).
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elseif ast.tag == 'Fornum' then
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blockrecurse = 1
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elseif ast.tag == 'Forin' then
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blockrecurse = 1
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end
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-- recurse (depth-first search down the AST)
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if ast.tag == 'Repeat' then
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local block_ast, cond_ast = ast[1], ast[2]
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local scope = scope
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for _,stat_ast in ipairs(block_ast) do
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scope = setmetatable({}, {__index = scope})
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traverse(stat_ast, scope, globals, level+1, functionlevel)
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end
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scope = setmetatable({}, {__index = scope})
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traverse(cond_ast, scope, globals, level+1, functionlevel)
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elseif ast.tag == 'Fornum' then
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local name_ast, block_ast = ast[1], ast[#ast]
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-- eval value list in current scope
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for i=2, #ast-1 do traverse(ast[i], scope, globals, level+1, functionlevel) end
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-- eval body in next scope
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local name = name_ast[1]
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definelocal(scope, name, name_ast)
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name_ast.localdefinition = name_ast
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name_ast.functionlevel = functionlevel
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traverse(block_ast, scope, globals, level+1, functionlevel)
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elseif ast.tag == 'Forin' then
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local namelist_ast, vallist_ast, block_ast = ast[1], ast[2], ast[3]
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-- eval value list in current scope
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traverse(vallist_ast, scope, globals, level+1, functionlevel)
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-- eval body in next scope
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for _,name_ast in ipairs(namelist_ast) do
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local name = name_ast[1]
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definelocal(scope, name, name_ast)
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name_ast.localdefinition = name_ast
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name_ast.functionlevel = functionlevel
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name_ast.level = level+1
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end
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traverse(block_ast, scope, globals, level+1, functionlevel)
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else -- normal
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for i,v in ipairs(ast) do
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if i ~= blockrecurse and type(v) == 'table' then
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local scope = setmetatable({}, {__index = scope})
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traverse(v, scope, globals, level+1, functionlevel)
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end
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end
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end
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-- operations on walking up the AST
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if ast.tag == 'Local' then
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-- Unlike Localrec, variables come into scope after evaluating values.
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local namelist_ast, valuelist_ast = ast[1], ast[2]
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for _,name_ast in ipairs(namelist_ast) do
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assert(name_ast.tag == 'Id')
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local name = name_ast[1]
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local parentscope = getmetatable(scope).__index
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definelocal(parentscope, name, name_ast)
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name_ast.localdefinition = name_ast
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name_ast.functionlevel = functionlevel
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name_ast.level = level+1
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end
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elseif ast.tag == 'Index' then
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if ast[2].tag == 'String' then
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ast[2].isfield = true
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ast[2].previous = ast[1]
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end
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elseif ast.tag == 'Invoke' then
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assert(ast[2].tag == 'String')
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ast[2].isfield = true
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ast[2].previous = ast[1]
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end
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end
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function M.globals(ast)
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-- Default list of defined variables.
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local scope = setmetatable({}, {})
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local globals = {}
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traverse(ast, scope, globals, 1, 1) -- Start check.
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return globals
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end
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-- Gets locals in scope of statement of block ast. If isafter is true and ast is statement,
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-- uses scope just after statement ast.
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-- Assumes 'parent' attributes on ast are marked.
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-- Returns table mapping name -> AST local definition.
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function M.variables_in_scope(ast, isafter)
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local scope = {}
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local cast = ast
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while cast.parent do
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local midx = LA.ast_idx(cast.parent, cast)
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for idx=1,midx do
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local bast = cast.parent[idx]
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if bast.tag == 'Localrec' or bast.tag == 'Local' and (idx < midx or isafter) then
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local names_ast = bast[1]
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for bidx=1,#names_ast do
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local name_ast = names_ast[bidx]
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local name = name_ast[1]
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scope[name] = name_ast
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end
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elseif cast ~= ast and (bast.tag == 'For' or bast.tag == 'Forin' or bast.tag == 'Function') then
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local names_ast = bast[1]
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for bidx=1,#names_ast do
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local name_ast = names_ast[bidx]
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if name_ast.tag == 'Id' then --Q: or maybe `Dots should be included
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local name = name_ast[1]
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scope[name] = name_ast
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end
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end
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end
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end
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cast = cast.parent
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end
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return scope
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end
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return M
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