MLStyle.Modules.AST

@matchast

• Description: Similar to @match, but the focus is on AST matching. There is no need to quote patterns with quote ... end or :(...).

• Usage: @matchast ast_to_match (begin cases... end)

• Examples:

julia> @matchast :(1 + 1) quote
           $a + 1 => a + 2
       end
3

is equivalent to

julia> @match :(1 + 1) begin
           :($a + 1) => a + 2
       end
3

Capture

Capture is a pattern, which could peek the scope(a Dict{Symbol, T}) at some point during the pattern matching. The scope only consists of the variables that MLStyle can aware of. Outer local variables and global variables cannot appear in the returned dictionary.

julia> @switch (1, 2, 3) begin
           @case (Capture(s1), Capture(s2), Capture(s3))
               println(s1)
               println(s2)
               println(s3)
       end       
Dict{Any,Any}()
Dict{Symbol,Dict{Any,Any}}(:s1 => Dict())
Dict{Symbol,Dict}(:s1 => Dict{Any,Any}(),:s2 => Dict{Symbol,Dict{Any,Any}}(:s1 => Dict()))

@capture

• Description: Similar to MacroTools.@capture, but provides a more regex-flavored matching.

• Usage: @capture template input_ast, note that template is purely static and cannot be a variable from current context.

• Examples:

func_node = :(f(a, b, c))
let_node = :(let a = b; a + b end)
@info :function @capture $fn($(args...)) func_node
@info :let @capture let $a = $b; $(stmts...) end let_node

outputs

┌ Info: function
│   #= REPL[9]:1 =# @capture ($(Expr(:$, :fn)))($(Expr(:$, :(args...)))) func_node =
│    Dict{Symbol,Any} with 2 entries:
│      :args => Any[:a, :b, :c]
└      :fn   => :f

┌ Info: let
│   #= REPL[10]:1 =# @capture let $(Expr(:$, :a)) = $(Expr(:$, :b))
        #= REPL[10]:1 =#
        $(Expr(:$, :(stmts...)))
    end let_node =
│    Dict{Symbol,Any} with 3 entries:
│      :a     => :a
│      :b     => :b
└      :stmts => Any[:(#= REPL[8]:1 =#), :(a + b)]