nomsu/lib/metaprogramming.nom

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#..
This File contains rules for making rules and macros and some helper functions to make
that easier.
# Rule to make rules:
lua code ".."
|nomsu:def("escaped rule %rule_def = %body", function(nomsu, vars)
| local aliases = nomsu:typecheck(vars, "rule_def", "Block").value
| local body = nomsu:typecheck(vars, "body", "Block")
| local thunk = nomsu:tree_to_value({type="Thunk", value={type="Statements", value=body.value, src=body.src}, src=body.src})
| local canonical = aliases[1]
| nomsu:def(canonical, thunk, body.src)
| local function rewriter(nomsu, vars)
| return nomsu:tree_to_lua(nomsu:replaced_vars(canonical, vars))
| end
| for i=2,#aliases do
| nomsu:defmacro(aliases[i], rewriter, body.src)
| end
|end)
# Rule to make nomsu macros:
escaped rule \(escaped parse %shorthand as %longhand) = \:
lua code ".."
|local aliases = nomsu:typecheck(vars, "shorthand", "Block").value
|local template = nomsu:typecheck(vars, "longhand", "Block")
|local function parsing_as(nomsu, vars)
| local replacement = nomsu:replaced_vars(template, vars)
| return nomsu:tree_to_lua(replacement)
|end
|for _,call in ipairs(aliases) do
| nomsu:defmacro(call, parsing_as, template.src)
|end
escaped parse \(parse %shorthand as %longhand) as \: escaped parse \%shorthand as \%longhand
parse (rule %rule_def = %body) as: escaped rule \%rule_def = \%body
# Rule to make lua macros:
rule (escaped compile %macro_def to %body) =:
lua code ".."
|local aliases = nomsu:typecheck(vars, "macro_def", "Block").value
|local body = nomsu:typecheck(vars, "body", "Block")
|local thunk = nomsu:tree_to_value({type="Thunk", value={type="Statements", value=body.value, src=body.src}, src=body.src})
|for _,alias in ipairs(aliases) do
| nomsu:defmacro(alias, thunk, body.src)
|end
rule (escaped compile %macro_def to code %body) =:
lua code ".."
|local aliases = nomsu:typecheck(vars, "macro_def", "Block").value
|local body = nomsu:typecheck(vars, "body", "Block")
|local thunk = nomsu:tree_to_value({type="Thunk", value={type="Statements", value=body.value, src=body.src}, src=body.src})
|local thunk2 = function(nomsu, vars) return nil, thunk(nomsu, vars) end
|for _,alias in ipairs(aliases) do
| nomsu:defmacro(alias, thunk2)
|end
parse (compile %macro_def to %body) as: escaped compile \%macro_def to \%body
parse (compile %macro_def to code %body) as: escaped compile \%macro_def to code \%body
parse (compile %macro_def to block %body) as: escaped compile \%macro_def to code\: ".."
|do
| \(%body)
|end
rule (%tree as lua) =:
lua expr "nomsu:tree_to_lua(\(%tree))"
rule (%tree as value) =:
lua expr "nomsu:tree_to_value(\(%tree), vars)"
compile (repr %obj) to:
"nomsu:repr(\(%obj as lua))"
parse (lua block %block) as: lua code ".."
|do
| \(%block)
|end
rule (%tree as lua statement) =:
lua block ".."
|local _,statement = nomsu:tree_to_lua(\(%tree))
|return statement
rule (%tree as lua statements) =:
lua block ".."
|local statements_tree = {type='Statements', value=\(%tree).value, src=\(%tree).src}
|local _,statements = nomsu:tree_to_lua(statements_tree)
|return statements
compile (nomsu) to: "nomsu"
compile (nomsu's %key) to: "nomsu[\(%key as lua)]"
compile (nomsu %method %args) to: "nomsu[\(%method as lua)](nomsu, unpack(\(%args as lua)))"
# Get the source code for a function
rule (help %rule) =:
lua block ".."
|local fn_def = nomsu:get_fn_def(vars.rule)
|if not fn_def then
| nomsu:writeln("Rule not found: "..nomsu:repr(vars.rule))
|else
| nomsu:writeln("rule "..nomsu:repr(nomsu.utils.keys(fn_def.invocation))
| .." ="..(fn_def.src or ":\\n <unknown source code>"))
|end
# Compiler tools
parse (eval %code; run %code) as: nomsu "run" [%code]
rule (source code from tree %tree) =:
lua block ".."
|local _,_,leading_space = vars.tree.src:find("\\n(%s*)%S")
|if leading_space then
| local chunk1, chunk2 = vars.tree.src:match(":%s*([^\\n]*)(\\n.*)")
| chunk2 = chunk2:gsub("\\n"..leading_space, "\\n")
| return chunk1..chunk2.."\\n"
|else
| return vars.tree.src:match(":%s*(%S.*)").."\\n"
|end
parse (source code %body) as: source code from tree \%body
parse (parse tree %code) as: nomsu "tree_to_str" [\%code]
parse (enable debugging) as: lua code "nomsu.debug = true"
parse (disable debugging) as: lua code "nomsu.debug = false"