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# tangle.jl:
# =========
# Convert Julia AST:s to DAG:s in dag.jl format
#
load("utils/req.jl")
req("dag/dag.jl")
# == TangleContext ============================================================
typealias SymbolTable Dict{Symbol,Node}
type TangleContext
symbols::SymbolTable # current symbol bindings
last_line::Node
last_actions#::Nodes # todo: add back once type inference bug is fixed
TangleContext() = new(SymbolTable(), NoNode(), ActionNode[])
end
function emit_line(c::TangleContext, node::Node)
c.last_line = isa(c.last_line, NoNode) ? node : KnotNode(c.last_line, node)
end
function emit_line(c::TangleContext, node::Node, name::Symbol)
emitted = emit_line(c, node); emitted.name = name
emitted
end
# == tangle ===================================================================
tangle(code) = raw_tangle(code)[1]
function raw_tangle(code)
context = TangleContext()
value = tangle(context, code)
if is((value::Node).name, nothing); value.name = :value; end
# sink = TupleNode(context.last_line, context.last_actions..., value)
sink = TupleNode(context.last_actions..., value)
#sink.name = :sink
sink, context
end
tangle(c::TangleContext, exps::Vector) = Node[{tangle(c, ex) | ex in exps}...]
tangle(c::TangleContext, ex::Any) = LiteralNode(ex) # literal
function tangle(c::TangleContext, name::Symbol)
@setdefault c.symbols[name] SymNode(name, name==:(...) ? :symbol : :input)
end
function tangle(context::TangleContext, ex::Expr)
if ex.head == :block # exprs...
value = LiteralNode(nothing)
for subex in ex.args; value = tangle(context, subex); end
return value
elseif ex.head == :(=) # assignment: lvalue = expr
lhs = tangle_lhs(context, ex.args[1])
rhs = tangle(context, ex.args[2])
return entangle_assignment(context, lhs, rhs)
elseif ex.head == :call
fname = ex.args[1]
op = @setdefault context.symbols[fname] SymNode(fname, :call)
args = tangle(context, ex.args[2:end])
return CallNode(op, args...)
elseif ex.head == :ref; return RefNode(tangle(context, ex.args)...)
# todo: test!:
elseif ex.head == :(...); return EllipsisNode(tangle(context, ex.args)...)
# todo: test!:
elseif ex.head == :tuple; return TupleNode(tangle(context, ex.args)...)
elseif ex.head == :line; return NoNode() # ignore line numbers
end
error("unexpected scalar rhs: ex = $ex")
end
# -- tangle_lhs --------------------------------------------------------------
# Tangle a scalar-valued lhs expr; return lone symbols unadorned
tangle_lhs(context::TangleContext, name::Symbol) = name
function tangle_lhs(context::TangleContext, ex::Expr)
# lvalue for indexed assignment
@expect is_expr(ex, :ref)
oname = ex.args[1]
output = @setdefault context.symbols[oname] SymNode(oname, :output)
inds = tangle(context, ex.args[2:end])
RefNode(output, inds...)
end
# -- entangle_assignment(context::TangleContext, lhs, rhs) --------------------
# Process assignment lhs = rhs.
# Returns value = rhs
function entangle_assignment(context::TangleContext, dest::Symbol, rhs::Node)
# straight assignment: just store in symbol table
context.symbols[dest] = emit_line(context, rhs, dest) # return rhs
end
function entangle_assignment(context::TangleContext, lhs::RefNode, rhs::Node)
# Indexed assignment to output
dest = get_A(lhs)::SymNode
node = AssignNode(lhs, rhs, context.last_actions...)
# bind the AssignNode to the name of dest
context.symbols[dest.val.name] = emit_line(context, node)
context.last_actions = [node]
rhs # and evaluate to the rhs
end
# == Some printing ============================================================
function print_list(list::Vector)
for item in list; println("\t", item); end
end
print_symtable(st::SymbolTable) = (for (k, v) in st; println("\t$k = $v"); end)
function print_context(context::TangleContext)
println("Symbols at end:")
print_symtable(context.symbols)
end
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