Merge branch 'lecture_09' of https://github.com/JuliaTeachingCTU/Scientific-Programming-in-Julia into lecture_09

Author: pevnak

docs/src/lecture_09/argcheck.jl

@@ -0,0 +1,91 @@
+using MacroTools
+using IRTools
+
+using IRTools: branches, block, empty!, evalir, func, branch!, block, IR, @dynamo, xcall
+
+function _mark(label, ex)
+    label isa Symbol || error("label has to be a Symbol")
+    return Expr(
+        :block,
+        Expr(:meta, :begin_optional, label),
+        esc(ex),
+        Expr(:meta, :end_optional, label),
+    )
+end
+
+macro mark(label, ex)
+    _mark(label, ex)
+end
+
+
+foo(x) = bar(baz(x))
+
+function bar(x)
+    @mark print iseven(x) && println("The input is even.")
+    x
+end
+
+function baz(x)
+    @mark print x<0 && println("The input is negative.")
+    x
+end
+
+
+
+isbegin(e::Expr) = Meta.isexpr(e,:meta) && e.args[1]===:begin_optional
+isend(e::Expr) = Meta.isexpr(e,:meta) && e.args[1]===:end_optional
+
+
+skip(f::Core.IntrinsicFunction, args...) = f(args...)
+skip(f::Core.Builtin, args...) = f(args...)
+
+@dynamo function skip(args...)
+    ir = IR(args...)
+    delete_line = false
+    local orig
+
+    for (x,st) in ir
+        is_begin = isbegin(st.expr)
+        is_end   = isend(st.expr)
+
+        if is_begin
+            delete_line = true
+        end
+    
+        if is_begin
+            orig = block(ir,x)
+        elseif is_end
+            dest = block(ir,x)
+            if orig != dest
+                empty!(branches(orig))
+                branch!(orig,dest)
+            end
+        end
+
+        if delete_line
+            delete!(ir,x)
+        end
+
+        if is_end
+            delete_line = false
+        end
+
+        if haskey(ir,x) && Meta.isexpr(st.expr,:call)
+            ir[x] = IRTools.xcall(skip, st.expr.args...)
+        end
+    end
+    return ir
+end
+
+function skip(ex::Expr)
+end
+
+macro skip(ex)
+    ex.head == :call || error("Input expression has to be a `:call`.")
+    return xcall(skip, ex.args...)
+end
+
+display(@code_ir foo(-2))
+display(@code_ir skip(foo,-2))
+display(foo(-2))
+@skip foo(-2)