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anselme/anselme/parser/expression/secondary/infix/infix_or_suffix.lua

32 lines
1.2 KiB
Lua

-- same as infix, but skip if no valid expression after the operator instead of erroring
-- useful for operators that are both valid as infix and as suffix
local infix = require("anselme.parser.expression.secondary.infix.infix")
local escape = require("anselme.common").escape
local expression_to_ast = require("anselme.parser.expression.to_ast")
return infix {
-- returns exp, rem if expression found
-- returns nil if no expression found
search = function(self, source, str, limit_pattern, current_priority, operating_on_primary)
if not self:match(str, current_priority, operating_on_primary) then
return nil
end
return self:maybe_parse(source, str, limit_pattern, current_priority, operating_on_primary)
end,
parse = function() error("no guaranteed parse for this operator") end,
-- return AST, rem
-- return nil
maybe_parse = function(self, source, str, limit_pattern, current_priority, primary)
local start_source = 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 return nil end
return self:build_ast(primary, right):set_source(start_source), rem
end,
}