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Code cleanup in symbolic.jl #29

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Oct 24, 2013
Merged

Code cleanup in symbolic.jl #29

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91 changes: 46 additions & 45 deletions src/symbolic.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -79,20 +79,21 @@ SymbolParameter(s::Symbol) = SymbolParameter{s}()
#
#################################################################

isnumber(a) = isa(a, Number)

# Numbers and symbols can't be simplified further
simplify(x) = x
simplify(n::Number) = n
simplify(s::SymbolicVariable) = s

# The default is just to simplify arguments.
simplify{T}(x::SymbolParameter{T}, args) = Expr(:call, T, map(x -> simplify(x), args)...)
simplify{T}(x::SymbolParameter{T}, args) = Expr(:call, T, map(simplify, args)...)

function simplify(ex::Expr)
if ex.head != :call
return ex
end
if all(map(a -> isa(a, Number), ex.args[2:end]))
if all(map(isnumber, ex.args[2:end]))
return eval(ex)
end
new_ex = simplify(SymbolParameter(ex.args[1]), ex.args[2:end])
Expand All @@ -106,10 +107,10 @@ function sum_numeric_args(args)
sum = 0
sym_args = {}
for arg in args
if isa(arg, Number)
if isnumber(arg)
sum += arg
else
sym_args = [sym_args, arg]
push!(sym_args, arg)
end
end
(sum, sym_args)
Expand All @@ -119,94 +120,94 @@ function mul_numeric_args(args)
prod = 1
sym_args = {}
for arg in args
if isa(arg, Number)
if isnumber(arg)
prod *= arg
else
sym_args = [sym_args, arg]
push!(sym_args, arg)
end
end
(prod, sym_args)
end

# Handles `args` of all lengths
# Removes any 0's in a sum
# Handle `args` of all lengths
function simplify(::SymbolParameter{:+}, args)
new_args = map(x -> simplify(x), filter(x -> x != 0, args))
if length(new_args) == 0
# Remove any 0's in a sum
args = map(simplify, filter(x -> x != 0, args))
if length(args) == 0
return 0
# Special Case: simplify(:(+x)) == x
elseif length(new_args) == 1
return new_args[1]
elseif length(args) == 1
return args[1]
else
(sum, sym_args) = sum_numeric_args(new_args)
new_args = sum==0 ? sym_args : [sum, sym_args]
return Expr(:call, :+, new_args...)
(sum, sym_args) = sum_numeric_args(args)
args = sum==0 ? sym_args : [sum, sym_args]
return Expr(:call, :+, args...)
end
end

# Assumes length(args) == 3
# Removes any 0's in a subtraction
# Assume length(args) == 3
function simplify(::SymbolParameter{:-}, args)
new_args = map(x -> simplify(x), filter(x -> x != 0, args))
if length(new_args) == 0
# Remove any 0's in a subtraction
args = map(simplify, filter(x -> x != 0, args))
if length(args) == 0
return 0
# Special Case: simplify(:(x - x)) == 0
elseif length(new_args) == 2 && new_args[1] == new_args[2]
elseif length(args) == 2 && args[1] == args[2]
return 0
else
return Expr(:call, :-, new_args...)
return Expr(:call, :-, args...)
end
end

# Handles `args` of all lengths
# Removes any 1's in a product
# Handle `args` of all lengths
function simplify(::SymbolParameter{:*}, args)
new_args = map(x -> simplify(x), filter(x -> x != 1, args))
if length(new_args) == 0
# Remove any 1's in a product
args = map(simplify, filter(x -> x != 1, args))
if length(args) == 0
return 1
# Special Case: simplify(:(*(x))) == x
elseif length(new_args) == 1
return new_args[1]
elseif length(args) == 1
return args[1]
# Special Case: simplify(:(x * y * z * 0)) == 0
elseif any(new_args .== 0)
elseif any(args .== 0)
return 0
else
(prod, sym_args) = mul_numeric_args(new_args)
new_args = prod==1 ? sym_args : [prod, sym_args]
return Expr(:call, :*, new_args...)
(prod, sym_args) = mul_numeric_args(args)
args = prod==1 ? sym_args : [prod, sym_args]
return Expr(:call, :*, args...)
end
end

# Assumes length(args) == 3
# Assume length(args) == 3
function simplify(::SymbolParameter{:/}, args)
new_args = map(x -> simplify(x), args)
args = map(simplify, args)
# Special Case: simplify(:(x / 1)) == x
if new_args[2] == 1
return new_args[1]
if args[2] == 1
return args[1]
# Special Case: simplify(:(0 / x)) == 0
elseif new_args[1] == 0
elseif args[1] == 0
return 0
else
return Expr(:call, :/, new_args...)
return Expr(:call, :/, args...)
end
end

# Assumes length(args) == 3
# Assume length(args) == 3
function simplify(::SymbolParameter{:^}, args)
new_args = map(x -> simplify(x), args)
args = map(simplify, args)
# Special Case: simplify(:(x ^ 0)) == 1
if new_args[2] == 0
if args[2] == 0
return 1
# Special Case: simplify(:(x ^ 1)) == x
elseif new_args[2] == 1
return new_args[1]
elseif args[2] == 1
return args[1]
# Special Case: simplify(:(0 ^ x)) == 0
elseif new_args[1] == 0
elseif args[1] == 0
return 0
# Special Case: simplify(:(1 ^ x)) == 1
elseif new_args[1] == 1
elseif args[1] == 1
return 1
else
return Expr(:call, :^, new_args...)
return Expr(:call, :^, args...)
end
end