Merge pull request #1139 from TorkelE/replaceupdate

A fix for `occursin`

src/Symbolics.jl

@@ -55,6 +55,7 @@ import MacroTools: splitdef, combinedef, postwalk, striplines
 include("wrapper-types.jl")
 
 include("num.jl")
+
 include("rewrite-helpers.jl")
 include("complex.jl")
 

src/rewrite-helpers.jl

@@ -1,35 +1,28 @@
 """
-    replace(expr::Symbolic, rules...)
-Walk the expression and replace subexpressions according to `rules`. `rules`
+replacenode(expr::Symbolic, rules...)
+Walk the expression and replacenode subexpressions according to `rules`. `rules`
 could be rules constructed with `@rule`, a function, or a pair where the
-left hand side is matched with equality (using `isequal`) and is replaced by the right hand side.
+left hand side is matched with equality (using `isequal`) and is replacenoded by the right hand side.
 
 Rules will be applied left-to-right simultaneously,
 so only one pattern will be applied to any subexpression,
 and the patterns will only be applied to the input text,
-not the replacements.
+not the replacenodements.
 
 Set `fixpoint = true` to repeatedly apply rules until no
 change to the expression remains to be made.
 """
-function Base.replace(expr::Num, r::Pair, rules::Pair...)
-    _replace(unwrap(expr), r, rules...)
+function replacenode(expr::Num, r::Pair, rules::Pair...; fixpoint = false)
+    _replacenode(unwrap(expr), r, rules...)
 end
-
 # Fix ambiguity
-function Base.replace(expr::Num, rules...)
-    _replace(unwrap(expr), rules...)
-end
-
-function Base.replace(expr::Symbolic, rules...)
-    _replace(unwrap(expr), rules...)
-end
+replacenode(expr::Num, rules...; fixpoint = false) = _replacenode(unwrap(expr), rules...; fixpoint)
+replacenode(expr::Symbolic, rules...; fixpoint = false) = _replacenode(unwrap(expr), rules...; fixpoint)
+replacenode(expr::Symbolic, r::Pair, rules::Pair...; fixpoint = false) = _replacenode(expr, r, rules...; fixpoint)
+replacenode(expr::Number, rules...; fixpoint = false) = expr
+replacenode(expr::Number, r::Pair, rules::Pair...; fixpoint = false) = expr
 
-function Base.replace(expr::Symbolic, r::Pair, rules::Pair...)
-    _replace(expr, r, rules...)
-end
-
-function _replace(expr::Symbolic, rules...; fixpoint=false)
+function _replacenode(expr::Symbolic, rules...; fixpoint = false)
     rs = map(r -> r isa Pair ? (x -> isequal(x, r[1]) ? r[2] : nothing) : r, rules)
     R = Prewalk(Chain(rs))
     if fixpoint
@@ -40,32 +33,32 @@ function _replace(expr::Symbolic, rules...; fixpoint=false)
 end
 
 """
-    occursin(c, x)
+    hasnode(c, x)
 Returns true if any part of `x` fufills the condition given in c. c can be a function or an expression.
 If it is a function, returns true if x is true for any part of x. If c is an expression, returns
 true if x contains c.
 
 Examples:
 ```julia
 @syms x y
-Symbolics.occursin(x, log(x) + x + 1) # returns `true`.
-Symbolics.occursin(x, log(y) + y + 1) # returns `false`.
+hasnode(x, log(x) + x + 1) # returns `true`.
+hasnode(x, log(y) + y + 1) # returns `false`.
 ```
 
 ```julia
 @variables t X(t)
 D = Differential(t)
-Symbolics.occursin(Symbolics.is_derivative, X + D(X) + D(X^2)) # returns `true`.
+hasnode(Symbolics.is_derivative, X + D(X) + D(X^2)) # returns `true`.
 ```
 """
-function Base.occursin(r::Function, y::Union{Num, Symbolic})
-    _occursin(r, y)
+function hasnode(r::Function, y::Union{Num, Symbolic})
+    _hasnode(r, y)
 end
+hasnode(r::Num, y::Union{Num, Symbolic}) = occursin(unwrap(r), unwrap(y))
+hasnode(r::Symbolic, y::Union{Num, Symbolic}) = occursin(unwrap(r), unwrap(y))
+hasnode(r::Union{Num, Symbolic, Function}, y::Number) = false
 
-Base.occursin(r::Num, y::Num) = occursin(unwrap(r), unwrap(y))
-Base.occursin(r::Num, y::Symbolic) = occursin(unwrap(r), unwrap(y))
-
-function _occursin(r, y)
+function _hasnode(r, y)
     y = unwrap(y)
     if r isa Function
         if r(y)
@@ -75,7 +68,7 @@ function _occursin(r, y)
 
     if iscall(y)
         return r(operation(y)) ||
-                any(y->_occursin(r, y), arguments(y))
+                any(y->_hasnode(r, y), arguments(y))
     else
         return false
     end
@@ -129,6 +122,7 @@ function filterchildren!(r::Any, y, acc)
 end
 
 module RewriteHelpers
-import Symbolics: filterchildren, unwrap
-export replace, occursin, filterchildren, unwrap
+import Symbolics: replacenode, hasnode, filterchildren, unwrap
+export replacenode, hasnode, filterchildren, unwrap
+
 end

test/rewrite_helpers.jl

@@ -9,15 +9,26 @@ using Test
 D = Differential(t)
 my_f(x, y) = x^3 + 2y
 
-# Check replace function.
+# Check `replacenode` function.
 let
-    @test isequal(replace(X + X + X, X =>1), 3)
-    @test isequal(replace(X + X + X, Y => 1), 3X)
-    @test isequal(replace(X + X + X, X => Y), 3Y)
-    @test isequal(replace(X + Y^2 - Z, Y^2 => Z), X)
+    # Simple replacements.
+    @test isequal(replacenode(X + X + X, X =>1), 3)
+    @test isequal(replacenode(X + X + X, Y => 1), 3X)
+    @test isequal(replacenode(X + X + my_f(X, Z), X => Y), Y^3 + 2Y + 2Z)
+    @test isequal(replacenode(X + Y^2 - Z, Y^2 => Z), X)
+
+    # When the rule is a function.
+    rep_func(expr) = Symbolics.is_derivative(expr) ? b : expr
+    @test isequal(replacenode(D(X + Y) - log(a*Z), rep_func), b - log(a*Z))
+    @test isequal(replacenode(D(Z^2) + my_f(D(X), D(Y)) + Z, rep_func), b^3 + 3b + Z)
+    @test isequal(replacenode(X + sin(Y + a) + a, rep_func), X + sin(Y + a) + a)
+
+    # On non-symbolic inputs.
+    @test isequal(replacenode(1, X =>2.0), 1)
+    @test isequal(replacenode(1, rep_func), 1)
 end
 
-# Test occursin function.
+# Test `hasnode` function.
 let
     ex1 = 2X^a - log(b + my_f(Y,Y)) - 3
     ex2 = X^(Y^(Z-a)) +log(log(log(b)))
@@ -26,39 +37,44 @@ let
     ex5 = a + 5b^2
 
     # Test for variables.
-    @test occursin(X, ex1)
-    @test occursin(X, ex2)
-    @test occursin(X, ex3)
-    @test !occursin(X, ex4)
-    @test occursin(Y, ex1)
-    @test occursin(Y, ex2)
-    @test occursin(Y, ex3)
-    @test occursin(Y, ex4)
-    @test !occursin(Z, ex1)
-    @test occursin(Z, ex2)
-    @test !occursin(Z, ex3)
-    @test occursin(Z, ex4)
+    @test hasnode(X, ex1)
+    @test hasnode(X, ex2)
+    @test hasnode(X, ex3)
+    @test !hasnode(X, ex4)
+    @test hasnode(Y, ex1)
+    @test hasnode(Y, ex2)
+    @test hasnode(Y, ex3)
+    @test hasnode(Y, ex4)
+    @test !hasnode(Z, ex1)
+    @test hasnode(Z, ex2)
+    @test !hasnode(Z, ex3)
+    @test hasnode(Z, ex4)
 
     # Test for variables.
-    @test_broken occursin(a, ex1)
-    @test_broken occursin(a, ex2)
-    @test_broken occursin(a, ex3)
-    @test_broken occursin(a, ex4)
-    @test occursin(a, ex5)
-    @test_broken occursin(b, ex1)
-    @test_broken occursin(b, ex2)
-    @test !occursin(b, ex3)
-    @test !occursin(b, ex4)
-    @test occursin(b, ex5)
+    @test hasnode(a, ex1)
+    @test hasnode(a, ex2)
+    @test hasnode(a, ex3)
+    @test hasnode(a, ex4)
+    @test hasnode(a, ex5)
+    @test hasnode(b, ex1)
+    @test hasnode(b, ex2)
+    @test !hasnode(b, ex3)
+    @test !hasnode(b, ex4)
+    @test hasnode(b, ex5)
 
     # Test for function.
-    @test !occursin(is_derivative, ex1)
-    @test !occursin(is_derivative, ex2)
-    @test !occursin(is_derivative, ex3)
-    @test occursin(is_derivative, ex4)
+    @test !hasnode(is_derivative, ex1)
+    @test !hasnode(is_derivative, ex2)
+    @test !hasnode(is_derivative, ex3)
+    @test hasnode(is_derivative, ex4)
+
+    # On non symbolic inputs:
+    @test !hasnode(X, 1)
+    @test !hasnode(a, 1)
+    @test !hasnode(is_derivative, 1)
 end
 
-# Check filterchildren function.
+# Check `filterchildren` function.
 let 
     ex1 = 2X^a - log(b + my_f(Y,Y)) - 3
     ex2 = X^(Y^(Z-a)) +log(log(log(b)))
@@ -80,8 +96,7 @@ let
     @test isequal(filterchildren(Z, ex3), [])
     @test isequal(filterchildren(Z, ex4), [Z])
 
-    # Test for variables.
-
+    # Test for syms.
     @test isequal(filterchildren(a, ex1), [a])
     @test isequal(filterchildren(a, ex2), [a])
     @test isequal(filterchildren(a, ex3), [a])