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] = false, false
27 if parent then weaveable [parent] = false end
29 weaveable [ast] = true
31 ast_children [ast] = { }
32 ast_parent [ast] = parent
33 if parent then table.insert (ast_children [parent], ast) end
36 -------------------------------------------------------------------
37 -- Visit up, from leaves to upper-level nodes, and weave leaves
38 -- back into the text of their parent node, recursively. Since the
39 -- visitor is imperative, we can't easily make it return a value
40 -- (the resulting recomposed source, here). Therefore we
41 -- imperatively store results in the association table
43 -------------------------------------------------------------------
46 local function acc(x) table.insert (_acc, x) end
48 -- ast Can't be weaved normally, try something else --
49 local function synthetize (ast)
51 acc (table.tostring (ast, 'nohash', 80, 8))
55 -- regular weaving of chidren in the parent's sources --
56 local function weave (ast)
57 local li = ast.lineinfo
58 if not li then return synthetize (ast) end
59 local a, d = li.first[3], li.last[3]
60 for child in ivalues (ast_children [ast]) do
61 local li = child.lineinfo
62 local b, c = li.first[3], li.last[3]
63 acc (src:sub (a, b-1))
64 acc (translation [child])
70 -- compute the translation from the children's ones --
71 if not translation [ast] then
72 if weaveable [ast] then weave (ast) else synthetize (ast) end
73 translation [ast] = table.concat (_acc)
77 local cfg = { expr=node; stat=node; block=node }
80 return translation [ast]
83 -- Get the source. If none is given, use itself as an example. --
84 local filename = arg[2] or arg[1] or arg[0]
85 local f = io.open (filename, 'r')
86 local src = f:read '*a'
89 local ast = mlc.luastring_to_ast (src, name)
91 print (weave_ast (src, ast))