From 6e5cbf9e7ebbabc01a974769b1aff27dc34d9af4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89tienne=20Reuh=20Fildadut?= <fildadut@reuh.eu>
Date: Sat, 4 Dec 2021 18:13:03 +0100
Subject: [PATCH] Add function references

---
 anselme.lua                            |  20 +---
 common.lua                             |  22 +++++
 interpreter/common.lua                 |   2 +
 interpreter/expression.lua             |  27 +++++-
 interpreter/interpreter.lua            |   4 +-
 parser/common.lua                      |  14 +--
 parser/expression.lua                  |  49 ++++++----
 parser/postparser.lua                  |   2 +-
 stdlib/bootscript.lua                  |   2 +
 stdlib/types.lua                       |   2 +-
 test/tests/function reference call.ans |  27 ++++++
 test/tests/function reference call.lua | 123 +++++++++++++++++++++++++
 12 files changed, 245 insertions(+), 49 deletions(-)
 create mode 100644 common.lua
 create mode 100644 test/tests/function reference call.ans
 create mode 100644 test/tests/function reference call.lua

diff --git a/anselme.lua b/anselme.lua
index 45f4df6..d8f8a2d 100644
--- a/anselme.lua
+++ b/anselme.lua
@@ -29,6 +29,7 @@ local identifier_pattern = require(anselme_root.."parser.common").identifier_pat
 local merge_state = require(anselme_root.."interpreter.common").merge_state
 local stdfuncs = require(anselme_root.."stdlib.functions")
 local bootscript = require(anselme_root.."stdlib.bootscript")
+local copy = require(anselme_root.."common").copy
 
 -- wrappers for love.filesystem / luafilesystem
 local function list_directory(path)
@@ -60,25 +61,6 @@ local function is_file(path)
 	end
 end
 
---- recursively copy a table, handle cyclic references, no metatable
-local function copy(t, cache)
-	if type(t) == "table" then
-		cache = cache or {}
-		if cache[t] then
-			return cache[t]
-		else
-			local c = {}
-			cache[t] = c
-			for k, v in pairs(t) do
-				c[k] = copy(v, cache)
-			end
-			return c
-		end
-	else
-		return t
-	end
-end
-
 --- interpreter methods
 local interpreter_methods = {
 	-- interpreter state
diff --git a/common.lua b/common.lua
new file mode 100644
index 0000000..a6f0e07
--- /dev/null
+++ b/common.lua
@@ -0,0 +1,22 @@
+local common
+common = {
+	--- recursively copy a table, handle cyclic references, no metatable
+	copy = function(t, cache)
+		if type(t) == "table" then
+			cache = cache or {}
+			if cache[t] then
+				return cache[t]
+			else
+				local c = {}
+				cache[t] = c
+				for k, v in pairs(t) do
+					c[k] = common.copy(v, cache)
+				end
+				return c
+			end
+		else
+			return t
+		end
+	end
+}
+return common
diff --git a/interpreter/common.lua b/interpreter/common.lua
index ab93ea9..7e56232 100644
--- a/interpreter/common.lua
+++ b/interpreter/common.lua
@@ -1,5 +1,6 @@
 local atypes, ltypes
 local eval, run_block
+local copy
 local common
 
 --- copy some text & process it to be suited to be sent to Lua in an event
@@ -393,5 +394,6 @@ local types = require((...):gsub("interpreter%.common$", "stdlib.types"))
 atypes, ltypes = types.anselme, types.lua
 eval = require((...):gsub("common$", "expression"))
 run_block = require((...):gsub("common$", "interpreter")).run_block
+copy = require((...):gsub("interpreter%.common$", "common")).copy
 
 return common
diff --git a/interpreter/expression.lua b/interpreter/expression.lua
index d0e1495..28bf5d5 100644
--- a/interpreter/expression.lua
+++ b/interpreter/expression.lua
@@ -1,5 +1,6 @@
 local expression
 local to_lua, from_lua, eval_text, is_of_type, truthy, format, pretty_type, get_variable, tags, eval_text_callback, events, flatten_list
+local copy
 
 local run
 
@@ -76,7 +77,7 @@ local function eval(state, exp)
 		events:pop_buffer(state)
 		if not v then return v, e end
 		return {
-			type = "eventbuffer",
+			type = "event buffer",
 			value = l
 		}
 	-- assignment
@@ -149,7 +150,12 @@ local function eval(state, exp)
 	elseif exp.type == "variable" then
 		return get_variable(state, exp.name)
 	-- function
-	elseif exp.type == "function" then
+	elseif exp.type == "function reference" then
+		return {
+			type = "function reference",
+			value = exp.names
+		}
+	elseif exp.type == "function call" then
 		-- eval args: list_brackets
 		local args = {}
 		if exp.argument then
@@ -157,6 +163,20 @@ local function eval(state, exp)
 			if not arg then return arg, arge end
 			args = arg.value
 		end
+		-- function reference: call the referenced function
+		local variants = exp.variants
+		if exp.called_name == "()" and args[1].type == "function reference" then
+			-- remove func ref as first arg
+			local refv = args[1].value
+			table.remove(args, 1)
+			-- get variants of the referenced function
+			variants = {}
+			for _, ffqm in ipairs(refv) do
+				for _, variant in ipairs(state.functions[ffqm]) do
+					table.insert(variants, variant)
+				end
+			end
+		end
 		-- map named arguments
 		local named_args = {}
 		for i, arg in ipairs(args) do
@@ -174,7 +194,7 @@ local function eval(state, exp)
 		-- try to select a function
 		local tried_function_error_messages = {}
 		local selected_variant = { depths = { assignment = nil }, variant = nil }
-		for _, fn in ipairs(exp.variants) do
+		for _, fn in ipairs(variants) do
 			-- checkpoint: no args, nothing to select on
 			if fn.type == "checkpoint" then
 				if not selected_variant.variant then
@@ -425,5 +445,6 @@ expression = require((...):gsub("interpreter%.expression$", "parser.expression")
 flatten_list = require((...):gsub("interpreter%.expression$", "parser.common")).flatten_list
 local common = require((...):gsub("expression$", "common"))
 to_lua, from_lua, eval_text, is_of_type, truthy, format, pretty_type, get_variable, tags, eval_text_callback, events = common.to_lua, common.from_lua, common.eval_text, common.is_of_type, common.truthy, common.format, common.pretty_type, common.get_variable, common.tags, common.eval_text_callback, common.events
+copy = require((...):gsub("interpreter%.expression$", "common")).copy
 
 return eval
diff --git a/interpreter/interpreter.lua b/interpreter/interpreter.lua
index 6e0e598..152065c 100644
--- a/interpreter/interpreter.lua
+++ b/interpreter/interpreter.lua
@@ -36,7 +36,7 @@ run_line = function(state, line)
 		v, e = eval(state, line.text)
 		if not v then return v, ("%s; at %s"):format(e, line.source) end
 		-- convert text events to choices
-		if v.type == "eventbuffer" then
+		if v.type == "event buffer" then
 			local current_tags = tags:current(state)
 			local choice_block_state = { tags = current_tags, block = line.child }
 			local final_buffer = {}
@@ -82,7 +82,7 @@ run_line = function(state, line)
 		if not v then return v, ("%s; in automatic event flush at %s"):format(e, line.source) end
 		v, e = eval(state, line.text)
 		if not v then return v, ("%s; at %s"):format(e, line.source) end
-		if v.type == "eventbuffer" then
+		if v.type == "event buffer" then
 			v, e = events:write_buffer(state, v.value)
 			if not v then return v, ("%s; at %s"):format(e, line.source) end
 		end
diff --git a/parser/common.lua b/parser/common.lua
index da0738b..b9d1e7d 100644
--- a/parser/common.lua
+++ b/parser/common.lua
@@ -174,7 +174,7 @@ common = {
 				if not exp then return nil, rem end
 				if not rem:match("^%s*}") then return nil, ("expected closing } at end of expression before %q"):format(rem) end
 				-- wrap in format() call
-				local variant, err = common.find_function_variant(state, namespace, "{}", { type = "parentheses", expression = exp }, true)
+				local variant, err = common.find_function(state, namespace, "{}", { type = "parentheses", expression = exp }, true)
 				if not variant then return variant, err end
 				-- add to text
 				table.insert(l, variant)
@@ -211,13 +211,13 @@ common = {
 			return text_exp
 		end
 	end,
-	-- find compatible function variants from a fully qualified name
-	-- this functions does not guarantee that functions are fully compatible with the given arguments and only performs a pre-selection without the ones which definitely aren't
-	-- * list of variants: if success
+	-- find a list of compatible function variants from a fully qualified name
+	-- this functions does not guarantee that the returned variants are fully compatible with the given arguments and only performs a pre-selection without the ones which definitely aren't
+	-- * list of compatible variants: if success
 	-- * nil, err: if error
 	find_function_variant_from_fqm = function(fqm, state, arg)
 		local err = ("compatible function %q variant not found"):format(fqm)
-		local func = state.functions[fqm] or {}
+		local func = state.functions[fqm]
 		local args = arg and common.flatten_list(arg) or {}
 		local variants = {}
 		for _, variant in ipairs(func) do
@@ -248,7 +248,7 @@ common = {
 	--- same as find_function_variant_from_fqm, but will search every function from the current namespace and up using find
 	-- returns directly a function expression in case of success
 	-- return nil, err otherwise
-	find_function_variant = function(state, namespace, name, arg, explicit_call)
+	find_function = function(state, namespace, name, arg, explicit_call)
 		local variants = {}
 		local err = ("compatible function %q variant not found"):format(name)
 		local l = common.find_all(state.aliases, state.functions, namespace, name)
@@ -263,7 +263,7 @@ common = {
 		end
 		if #variants > 0 then
 			return {
-				type = "function",
+				type = "function call",
 				called_name = name,
 				explicit_call = explicit_call,
 				variants = variants,
diff --git a/parser/expression.lua b/parser/expression.lua
index ed83ede..0d875f6 100644
--- a/parser/expression.lua
+++ b/parser/expression.lua
@@ -1,4 +1,4 @@
-local identifier_pattern, format_identifier, find, escape, find_function_variant, parse_text
+local identifier_pattern, format_identifier, find, escape, find_function, parse_text, find_all
 
 --- binop priority
 local binops_prio = {
@@ -132,7 +132,7 @@ local function expression(s, state, namespace, current_priority, operating_on)
 					right = val
 				}
 				-- find compatible variant
-				local variant, err = find_function_variant(state, namespace, ":", args, true)
+				local variant, err = find_function(state, namespace, ":", args, true)
 				if not variant then return variant, err end
 				return expression(r, state, namespace, current_priority, variant)
 			end
@@ -171,9 +171,22 @@ local function expression(s, state, namespace, current_priority, operating_on)
 				end
 			end
 			-- find compatible variant
-			local variant, err = find_function_variant(state, namespace, name, args, explicit_call)
+			local variant, err = find_function(state, namespace, name, args, explicit_call)
 			if not variant then return variant, err end
 			return expression(r, state, namespace, current_priority, variant)
+		-- function reference
+		elseif s:match("^%&"..identifier_pattern) then
+			local name, r = s:match("^%&("..identifier_pattern..")(.-)$")
+			name = format_identifier(name)
+			-- get all functions this name can reference
+			local lfnqm = find_all(state.aliases, state.functions, namespace, name)
+			if #lfnqm > 0 then
+				return expression(r, state, namespace, current_priority, {
+					type = "function reference",
+					names = lfnqm
+				})
+			end
+			return nil, ("can't find function %q to reference"):format(name)
 		end
 		-- unops
 		for prio, oplist in ipairs(unops_prio) do
@@ -183,7 +196,7 @@ local function expression(s, state, namespace, current_priority, operating_on)
 					local right, r = expression(s:match("^"..escaped.."(.*)$"), state, namespace, prio)
 					if not right then return nil, ("invalid expression after unop %q: %s"):format(op, r) end
 					-- find variant
-					local variant, err = find_function_variant(state, namespace, op, right, true)
+					local variant, err = find_function(state, namespace, op, right, true)
 					if not variant then return variant, err end
 					return expression(r, state, namespace, current_priority, variant)
 				end
@@ -227,7 +240,7 @@ local function expression(s, state, namespace, current_priority, operating_on)
 								}
 							end
 							-- find compatible variant
-							local variant, err = find_function_variant(state, namespace, name, args, explicit_call)
+							local variant, err = find_function(state, namespace, name, args, explicit_call)
 							if not variant then return variant, err end
 							return expression(r, state, namespace, current_priority, variant)
 						-- other binops
@@ -250,12 +263,12 @@ local function expression(s, state, namespace, current_priority, operating_on)
 										left = operating_on,
 										right = right
 									}
-									local variant, err = find_function_variant(state, namespace, op:match("^(.*)%=$"), args, true)
+									local variant, err = find_function(state, namespace, op:match("^(.*)%=$"), args, true)
 									if not variant then return variant, err end
 									right = variant
 								end
 								-- assign to a function
-								if operating_on.type == "function" then
+								if operating_on.type == "function call" then
 									-- remove non-assignment functions
 									for i=#operating_on.variants, 1, -1 do
 										if not operating_on.variants[i].assignment then
@@ -291,7 +304,7 @@ local function expression(s, state, namespace, current_priority, operating_on)
 									left = operating_on,
 									right = right
 								}
-								local variant, err = find_function_variant(state, namespace, op, args, true)
+								local variant, err = find_function(state, namespace, op, args, true)
 								if not variant then return variant, err end
 								return expression(r, state, namespace, current_priority, variant)
 							end
@@ -300,15 +313,19 @@ local function expression(s, state, namespace, current_priority, operating_on)
 				end
 			end
 		end
-		-- index
+		-- index / call
 		if s:match("^%b()") then
 			local content, r = s:match("^(%b())(.*)$")
-			-- get arguments (parentheses are kept)
-			local right, r_paren = expression(content, state, namespace)
-			if not right then return right, r_paren end
-			if r_paren:match("[^%s]") then return nil, ("unexpected %q at end of index expression"):format(r_paren) end
-			local args = { type = "list", left = operating_on, right = right }
-			local variant, err = find_function_variant(state, namespace, "()", args, true)
+			content = content:gsub("^%(", ""):gsub("%)$", "")
+			-- get arguments
+			local args = operating_on
+			if content:match("[^%s]") then
+				local right, r_paren = expression(content, state, namespace)
+				if not right then return right, r_paren end
+				if r_paren:match("[^%s]") then return nil, ("unexpected %q at end of index/call expression"):format(r_paren) end
+				args = { type = "list", left = args, right = right }
+			end
+			local variant, err = find_function(state, namespace, "()", args, true)
 			if not variant then return variant, err end
 			return expression(r, state, namespace, current_priority, variant)
 		end
@@ -319,6 +336,6 @@ end
 
 package.loaded[...] = expression
 local common = require((...):gsub("expression$", "common"))
-identifier_pattern, format_identifier, find, escape, find_function_variant, parse_text = common.identifier_pattern, common.format_identifier, common.find, common.escape, common.find_function_variant, common.parse_text
+identifier_pattern, format_identifier, find, escape, find_function, parse_text, find_all = common.identifier_pattern, common.format_identifier, common.find, common.escape, common.find_function, common.parse_text, common.find_all
 
 return expression
diff --git a/parser/postparser.lua b/parser/postparser.lua
index f8d85a1..6922f89 100644
--- a/parser/postparser.lua
+++ b/parser/postparser.lua
@@ -29,7 +29,7 @@ local function parse(state)
 					end
 					param.default = default_exp
 					-- extract type annotation from default value
-					if default_exp.type == "function" and default_exp.called_name == "::" then
+					if default_exp.type == "function call" and default_exp.called_name == "::" then
 						param.type_annotation = default_exp.argument.expression.right
 					end
 				end
diff --git a/stdlib/bootscript.lua b/stdlib/bootscript.lua
index 55028c6..78b3c60 100644
--- a/stdlib/bootscript.lua
+++ b/stdlib/bootscript.lua
@@ -6,4 +6,6 @@ return [[
 :string="string"
 :list="list"
 :pair="pair"
+:event buffer="event buffer"
+:function reference="function reference"
 ]]
diff --git a/stdlib/types.lua b/stdlib/types.lua
index 543e449..1f9a485 100644
--- a/stdlib/types.lua
+++ b/stdlib/types.lua
@@ -131,7 +131,7 @@ types.anselme = {
 			return { [k] = v }
 		end
 	},
-	eventbuffer = {
+	["event buffer"] = {
 		format = function(val)
 			local v, e = events:write_buffer(anselme.running.state, val)
 			if not v then return v, e end
diff --git a/test/tests/function reference call.ans b/test/tests/function reference call.ans
new file mode 100644
index 0000000..a985a25
--- /dev/null
+++ b/test/tests/function reference call.ans	
@@ -0,0 +1,27 @@
+$ f(x)
+	@x+2
+
+$ g(x)
+	@x+3
+
+:a = &f
+
+:b = &g
+
+3: {f(1)}
+
+3: {a(1)}
+
+5: {g(2)}
+
+4: {a(2)}
+
+4: {b(1)}
+
+5: {f(3)}
+
+13: {b(10)}
+
+7: {a(5)}
+
+8: {g(5)}
diff --git a/test/tests/function reference call.lua b/test/tests/function reference call.lua
new file mode 100644
index 0000000..125e47e
--- /dev/null
+++ b/test/tests/function reference call.lua	
@@ -0,0 +1,123 @@
+local _={}
+_[55]={}
+_[54]={}
+_[53]={}
+_[52]={}
+_[51]={}
+_[50]={}
+_[49]={}
+_[48]={}
+_[47]={}
+_[46]={}
+_[45]={}
+_[44]={}
+_[43]={}
+_[42]={}
+_[41]={}
+_[40]={}
+_[39]={}
+_[38]={}
+_[37]={text="8",tags=_[55]}
+_[36]={text="8: ",tags=_[54]}
+_[35]={text="7",tags=_[53]}
+_[34]={text="7: ",tags=_[52]}
+_[33]={text="13",tags=_[51]}
+_[32]={text="13: ",tags=_[50]}
+_[31]={text="5",tags=_[49]}
+_[30]={text="5: ",tags=_[48]}
+_[29]={text="4",tags=_[47]}
+_[28]={text="4: ",tags=_[46]}
+_[27]={text="4",tags=_[45]}
+_[26]={text="4: ",tags=_[44]}
+_[25]={text="5",tags=_[43]}
+_[24]={text="5: ",tags=_[42]}
+_[23]={text="3",tags=_[41]}
+_[22]={text="3: ",tags=_[40]}
+_[21]={text="3",tags=_[39]}
+_[20]={text="3: ",tags=_[38]}
+_[19]={_[36],_[37]}
+_[18]={_[34],_[35]}
+_[17]={_[32],_[33]}
+_[16]={_[30],_[31]}
+_[15]={_[28],_[29]}
+_[14]={_[26],_[27]}
+_[13]={_[24],_[25]}
+_[12]={_[22],_[23]}
+_[11]={_[20],_[21]}
+_[10]={"return"}
+_[9]={"text",_[19]}
+_[8]={"text",_[18]}
+_[7]={"text",_[17]}
+_[6]={"text",_[16]}
+_[5]={"text",_[15]}
+_[4]={"text",_[14]}
+_[3]={"text",_[13]}
+_[2]={"text",_[12]}
+_[1]={"text",_[11]}
+return {_[1],_[2],_[3],_[4],_[5],_[6],_[7],_[8],_[9],_[10]}
+--[[
+{ "text", { {
+      tags = {},
+      text = "3: "
+    }, {
+      tags = {},
+      text = "3"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "3: "
+    }, {
+      tags = {},
+      text = "3"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "5: "
+    }, {
+      tags = {},
+      text = "5"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "4: "
+    }, {
+      tags = {},
+      text = "4"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "4: "
+    }, {
+      tags = {},
+      text = "4"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "5: "
+    }, {
+      tags = {},
+      text = "5"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "13: "
+    }, {
+      tags = {},
+      text = "13"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "7: "
+    }, {
+      tags = {},
+      text = "7"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "8: "
+    }, {
+      tags = {},
+      text = "8"
+    } } }
+{ "return" }
+]]--
\ No newline at end of file