create Headers type that will safely and conviently deal with duplicates

README.md

@@ -19,7 +19,7 @@ This package provides types and helper functions for dealing with the HTTP proto
 ## Documentation
 ### Request
 
-A `Request` represents an HTTP request sent by a client to a server. 
+A `Request` represents an HTTP request sent by a client to a server.
 
     :::julia
     type Request
@@ -31,7 +31,7 @@ A `Request` represents an HTTP request sent by a client to a server.
 
 * `method` is an HTTP methods string ("GET", "PUT", etc)
 * `resource` is the url resource requested ("/hello/world")
-* `headers` is a `Dict` of field name `String`s to value `String`s
+* `headers` is an `Associative` of field name `String`s to value `String`s
 * `data` is the data in the request
 
 ### Response
@@ -47,7 +47,7 @@ A `Response` represents an HTTP response sent to a client by a server.
     end
 
 * `status` is the HTTP status code (see `STATUS_CODES`) [default: `200`]
-* `headers` is the `Dict` of headers [default: `headers()`, see Headers below]
+* `headers` is the headers [default: `headers()`, see Headers below]
 * `data` is the response data (as a `String` or `Array{Uint8}`) [default: `""`]
 * `finished` is `true` if the `Reponse` is valid, meaning that it can be converted to an actual HTTP response [default: `false`]
 
@@ -61,7 +61,11 @@ There are a variety of constructors for `Response`, which set sane defaults for
 
 ### Headers
 
-`Headers` is a type alias for `Dict{String,String}`.
+`Headers` is an `Associative{String,String}`. You can interact with it
+much like a Dict, but it can have multiple keys with the same
+value. For example `Set-Cookie` may be set multiple time for multiple
+cookies.
+
 There is a default constructor, `headers`, to produce a reasonable default set of headers.
 The defaults are as follows:
 

src/HttpCommon.jl

@@ -27,11 +27,12 @@ export STATUS_CODES,
        decodeURI,
        parsequerystring,
        FileResponse,
-       mimetypes
+       mimetypes,
+       headersforkey
 
 include("mimetypes.jl")
 
-import Base.show
+import Base: done, next, start, get, setindex!, delete!, show, length, convert
 
 const STATUS_CODES = Dict([
     (100, "Continue"),
@@ -129,16 +130,85 @@ RFC1123_datetime() = RFC1123_datetime(Dates.now(Dates.UTC))
 
 # HTTP Headers
 #
-# Dict Type for HTTP headers
+# Type for HTTP headers
 # `headers()` for building default Response Headers
 #
-typealias Headers Dict{String,String}
-headers() = Dict{String,String}([ 
+type Headers <: Associative{String, String}
+    data::Dict{String,Vector{String}}
+    length::Int
+end
+Headers() = Headers(Dict{String,Vector{String}}(), 0)
+Headers{K<:String,V<:String}(d::Associative{K,V}) = merge!(Headers(), d)
+headers() = Headers(Dict{String,String}([
     ("Server"            , "Julia/$VERSION"),
     ("Content-Type"      , "text/html; charset=utf-8"),
     ("Content-Language"  , "en"),
     ("Date"              , RFC1123_datetime())
-])
+]))
+
+convert{K<:String,V<:String}(::Type{Headers}, d::Associative{K,V}) = Headers(d)
+
+function start(h::Headers)
+    vals = (String)[]
+    (start(h.data), nothing, vals, start(vals))
+end
+
+function done(h::Headers, s)
+    dictst, key, vals, valsst = s
+    done(vals, valsst) && done(h.data, dictst)
+end
+
+function next(h::Headers, s)
+    dictst, key, vals, valsst = s
+    while done(vals, valsst)
+        ((key, vals), dictst) = next(h.data, dictst)
+        valsst = start(vals)
+    end
+    val, valsst = next(vals, valsst)
+    ((key, val), (dictst, key, vals, valsst))
+end
+
+function show(io::IO, h::Headers)
+    println(io, "Headers     :")
+    for (k,v) in h
+        println(io, "    $k: $v")
+    end
+end
+
+function get(h::Headers, k::String, default)
+    vs = get(h.data, k, nothing)
+    if is(vs, nothing)
+        return default
+    end
+    @assert length(vs) != 0
+    if length(vs) > 1
+        warn("getindex() called for header \"$k\" with multiple values")
+    end
+    vs[1]
+end
+
+function setindex!(h::Headers, v::String, k::String)
+    h.length += 1
+    if haskey(h.data, k)
+        push!(h.data[k], v)
+    else
+        h.data[k] = [v]
+    end
+    return h
+end
+
+function delete!(h::Headers, k::String)
+    vs = get(h.data, k, nothing)
+    if !is(vs, nothing)
+        h.length -= length(vs)
+    end
+    delete!(h.data, k)
+    h
+end
+
+length(h::Headers) = h.length
+
+headersforkey(h::Headers, k::String) = h.data[k]
 
 # HTTP request
 #
@@ -198,7 +268,7 @@ function FileResponse(filename)
         Response(200, Dict{String,String}([("Content-Type",mime)]), s)
     else
         Response(404, "Not Found - file $filename could not be found")
-    end         
+    end
 end
 
 # Escape HTML characters

test/runtests.jl

@@ -33,8 +33,34 @@ facts("HttpCommon utility functions") do
         @fact parsequerystring("foo=%3Ca%20href%3D%27foo%27%3Ebar%3C%2Fa%3Erun%26%2B%2B&bar=123") =>
             ["foo" => "<a href='foo'>bar</a>run&++", "bar" => "123"]
     end
-
 end
 
 # Check doesn't throw
-RFC1123_datetime()
+RFC1123_datetime()
+
+facts("Headers") do
+    context("Headers with duplicates") do
+        h = Headers()
+        @fact length(h) => 0
+
+        h["Content-Type"] = "text/html"
+        @fact length(h) => 1
+
+        h["Set-Cookie"] = "user=me;"
+        @fact length(h) => 2
+
+        h["Set-Cookie"] = "pass=secret;"
+        @fact length(h) => 3
+
+        @fact h["Content-Type"] => "text/html"
+        @fact headersforkey(h, "Set-Cookie") => ["user=me;", "pass=secret;"]
+        @fact h |> collect |> sort => [("Content-Type", "text/html"),
+                                       ("Set-Cookie", "pass=secret;"),
+                                       ("Set-Cookie", "user=me;")]
+
+        delete!(h, "Set-Cookie")
+        @fact length(h) => 1
+        @fact h["Content-Type"] => "text/html"
+        @fact get(h, "Set-Cookie", "**DEFAULT**") => "**DEFAULT**"
+    end
+end