4 function weave_ast (src, ast, name)
6 -------------------------------------------------------------------
7 -- translation: associate an AST node to its recomposed source
8 -- ast_children: associate an AST node to the list of its children
9 -- ast_parent: associate an AST node to the list of its parent
10 -- weavable: whether an AST node supports weaving of its children
11 -- node: common walker config for exprs, stats & blocks
12 -------------------------------------------------------------------
13 local translation, ast_children, ast_parent, weaveable, node =
14 { }, { }, { }, { }, { }
16 -------------------------------------------------------------------
17 -- Build up the parent/children relationships. This is not the same
18 -- as inclusion between tables: the relation we're building only
19 -- relates blocks, expressions and statements; in the AST, some
20 -- tables don't represent any of these node kinds.
21 -- For instance in `Local{ { `Id "x" }, { } }, `Id"x" is a child of
22 -- the `Local{ } node, although it's not directly included in it.
23 -------------------------------------------------------------------
24 function node.down(ast, parent)
25 if not ast.lineinfo then
26 weaveable [ast], weaveable [parent] = false, false
28 weaveable [ast] = true
30 ast_children [ast] = { }
31 ast_parent [ast] = parent
32 if parent then table.insert (ast_children [parent], ast) end
35 -------------------------------------------------------------------
36 -- Visit up, from leaves to upper-level nodes, and weave leaves
37 -- back into the text of their parent node, recursively. Since the
38 -- visitor is imperative, we can't easily make it return a value
39 -- (the resulting recomposed source, here). Therefore we
40 -- imperatively store results in the association table
42 -------------------------------------------------------------------
45 local function acc(x) table.insert (_acc, x) end
47 -- ast Can't be weaved normally, try something else --
48 local function synthetize (ast)
50 acc (table.tostring (ast, 'nohash', 80, 8))
54 -- regular weaving of chidren in the parent's sources --
55 local function weave (ast)
56 local li = ast.lineinfo
57 if not li then return synthetize (ast) end
58 local a, d = li.first[3], li.last[3]
59 for child in ivalues (ast_children [ast]) do
60 local li = child.lineinfo
61 local b, c = li.first[3], li.last[3]
62 acc (src:sub (a, b-1))
63 acc (translation [child])
69 -- compute the translation from the children's ones --
70 if not translation [ast] then
71 if weaveable [ast] then weave (ast) else synthetize (ast) end
72 translation [ast] = table.concat (_acc)
76 local cfg = { expr=node; stat=node; block=node }
79 return translation [ast]
82 -- Get the source. If none is given, use itself as an example. --
83 local filename = arg[2] or arg[1] or arg[0]
84 local f = io.open (filename, 'r')
85 local src = f:read '*a'
88 local ast = mlc.luastring_to_ast (src, name)
90 print (weave_ast (src, ast))