Anselme v2.0.0-alpha rewrite

Woke up and felt like changing a couple things. It's actually been worked on for a while, little at a time...

The goal was to make the language and implementation much simpler. Well I don't know if it really ended up being simpler but it sure is more robust.

Main changes:
* proper first class functions and closures supports! proper scoping rules! no more namespace shenanigans!
* everything is an expression, no more statements! make the implementation both simpler and more complex, but it's much more consistent now! the syntax has massively changed as a result though.
* much more organized and easy to modify codebase: one file for each AST node, no more random fields or behavior set by some random node exceptionally, everything should now follow the same API defined in ast.abstract.Node

Every foundational feature should be implemented right now. The vast majority of things that were possible in v2 are possible now; some things aren't, but that's usually because v2 is a bit more sane.
The main missing things before a proper release are tests and documentation. There's a few other things that might be implemented later, see the ideas.md file.

parser/expression/primary/prefix/else.lua

@@ -0,0 +1,8 @@
+local prefix_quote_right = require("parser.expression.primary.prefix.prefix_quote_right")
+local operator_priority = require("common").operator_priority
+
+return prefix_quote_right {
+	operator = "~",
+	identifier = "~_",
+	priority = operator_priority["~_"]
+}

parser/expression/primary/prefix/function.lua

@@ -0,0 +1,35 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+local parameter_tuple = require("parser.expression.contextual.parameter_tuple")
+local escape = require("common").escape
+local expression_to_ast = require("parser.expression.to_ast")
+
+local ast = require("ast")
+local Function, ParameterTuple = ast.Function, ast.ParameterTuple
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = "$",
+	priority = operator_priority["$_"],
+
+	parse = function(self, source, str, limit_pattern)
+		local source_start = source:clone()
+		local escaped = escape(self.operator)
+		local rem = source:consume(str:match("^("..escaped..")(.*)$"))
+
+		-- parse eventual parameters
+		local parameters
+		if parameter_tuple:match(rem) then
+			parameters, rem = parameter_tuple:parse(source, rem)
+		else
+			parameters = ParameterTuple:new()
+		end
+
+		-- parse expression
+		local s, right
+		s, right, rem = pcall(expression_to_ast, source, rem, limit_pattern, self.priority)
+		if not s then error(("invalid expression after unop %q: %s"):format(self.operator, right), 0) end
+
+		return Function:new(parameters, right):set_source(source_start), rem
+	end
+}

parser/expression/primary/prefix/mutable.lua

@@ -0,0 +1,9 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = "*",
+	identifier = "*_",
+	priority = operator_priority["*_"]
+}

parser/expression/primary/prefix/negation.lua

@@ -0,0 +1,9 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = "-",
+	identifier = "-_",
+	priority = operator_priority["-_"]
+}

parser/expression/primary/prefix/not.lua

@@ -0,0 +1,9 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = "!",
+	identifier = "!_",
+	priority = operator_priority["!_"]
+}

parser/expression/primary/prefix/prefix.lua

@@ -0,0 +1,34 @@
+-- unary prefix operators, for example: the - in -5
+
+local primary = require("parser.expression.primary.primary")
+local escape = require("common").escape
+local expression_to_ast = require("parser.expression.to_ast")
+
+local ast = require("ast")
+local Call, Identifier, ArgumentTuple = ast.Call, ast.Identifier, ast.ArgumentTuple
+
+return primary {
+	operator = nil,
+	identifier = nil,
+	priority = nil,
+
+	match = function(self, str)
+		local escaped = escape(self.operator)
+		return str:match("^"..escaped)
+	end,
+
+	parse = function(self, source, str, limit_pattern)
+		local source_start = source:clone()
+		local escaped = escape(self.operator)
+
+		local sright = source:consume(str:match("^("..escaped..")(.*)$"))
+		local s, right, rem = pcall(expression_to_ast, source, sright, limit_pattern, self.priority)
+		if not s then error(("invalid expression after prefix operator %q: %s"):format(self.operator, right), 0) end
+
+		return self:build_ast(right):set_source(source_start), rem
+	end,
+
+	build_ast = function(self, right)
+		return Call:new(Identifier:new(self.identifier), ArgumentTuple:new(right))
+	end
+}

parser/expression/primary/prefix/prefix_quote_right.lua

@@ -0,0 +1,11 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local ast = require("ast")
+local Call, Identifier, ArgumentTuple, Quote = ast.Call, ast.Identifier, ast.ArgumentTuple, ast.Quote
+
+return prefix {
+	build_ast = function(self, right)
+		right = Quote:new(right)
+		return Call:new(Identifier:new(self.identifier), ArgumentTuple:new(right))
+	end
+}

parser/expression/primary/prefix/return.lua

@@ -0,0 +1,15 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local ast = require("ast")
+local Return = ast.Return
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = "@",
+	priority = operator_priority["@_"],
+
+	build_ast = function(self, right)
+		return Return:new(right)
+	end
+}

parser/expression/primary/prefix/semicolon.lua

@@ -0,0 +1,13 @@
+local prefix = require("parser.expression.primary.prefix.prefix")
+
+local operator_priority = require("common").operator_priority
+
+return prefix {
+	operator = ";",
+	identifier = ";_",
+	priority = operator_priority[";_"],
+
+	build_ast = function(self, right)
+		return right
+	end
+}