Add code gen documentation

src/code_gen/main.jl

@@ -1,5 +1,16 @@
 using DataStructures
 
+"""
+    gen_code(graph::DAG)
+
+Generate the code for a given graph. The return value is a tuple of:
+
+    - `code::Expr`: The julia expression containing the code for the whole graph.
+    - `inputSymbols::Dict{String, Symbol}`: A dictionary of symbols mapping the names of the input nodes of the graph to the symbols their inputs should be provided on.
+    - `outputSymbol::Symbol`: The symbol of the final calculated value
+
+See also: [`execute`](@ref)
+"""
 function gen_code(graph::DAG)
     code = Vector{Expr}()
     sizehint!(code, length(graph.nodes))
@@ -39,6 +50,11 @@ function gen_code(graph::DAG)
     )
 end
 
+"""
+    execute(generated_code, input::Dict{ParticleType, Vector{Particle}})
+
+Execute the given generated_code (as returned by [`gen_code`](@ref)) on the given input particles.
+"""
 function execute(generated_code, input::Dict{ParticleType, Vector{Particle}})
     (code, inputSymbols, outputSymbol) = generated_code
     @assert length(input) == length(inputSymbols)
@@ -71,6 +87,14 @@ function execute(generated_code, input::Dict{ParticleType, Vector{Particle}})
     return result
 end
 
+"""
+    execute(graph::DAG, input::Dict{ParticleType, Vector{Particle}})
+
+Execute the given generated_code (as returned by [`gen_code`](@ref)) on the given input particles.
+The input particles should be sorted correctly into the dictionary to their according [`ParticleType`](@ref)s.
+
+See also: [`gen_particles`](@ref)
+"""
 function execute(graph::DAG, input::Dict{ParticleType, Vector{Particle}})
     (code, inputSymbols, outputSymbol) = gen_code(graph)