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Merge branch #16

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31 changes: 31 additions & 0 deletions errors.lua
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Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
local BAD_REQUEST = 400
local NOT_FOUND = 404
local INTERNAL = 500

local function new(code, text)
return setmetatable({
code = code,
text = text,
}, {
__tostring = function(self)
return ("Error %s: %s"):format(self.code, self.text)
end,
__index = {
is_bad_request = function(self) return self.code == BAD_REQUEST end,
is_not_found = function(self) return self.code == NOT_FOUND end,
is_internal = function(self) return self.code == INTERNAL end,
}
})
end

return {
bad_request = function(text)
return new(BAD_REQUEST, text)
end,
not_found = function(text)
return new(NOT_FOUND, text)
end,
internal = function(text)
return new(INTERNAL, text)
end,
}
123 changes: 89 additions & 34 deletions jsonpath.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,7 @@
local M = {}

local ffi = require('ffi')
local errors = require('errors')

-- Use Roberto Ierusalimschy's fabulous LulPeg pattern-matching library
local lulpeg = require('lulpeg')
Expand Down Expand Up @@ -419,7 +420,7 @@ end
--- @param rval any Right value of binary operator
--- @param op_str string String representation of operator, used in error reporting
--- @return any|nil val Result value
--- @return nil|string err Error, if cast has failed
--- @return nil|table err Error, if cast has failed
local function exec_binary_op(op, lval, rval, op_str)
local l_type = type(lval)
local r_type = type(rval)
Expand All @@ -440,18 +441,21 @@ local function exec_binary_op(op, lval, rval, op_str)
if l_type == "string" then
lval = tonumber(lval)
if lval == nil then
return nil, ("can not parse string lvalue as number for operation %s"):format(op_str)
return nil, errors.bad_request(
("can not parse string lvalue as number for operation %s"):format(op_str)
)
end
elseif l_type ~= "number" then
return nil, ("lvalue is not a number for operation %s"):format(op_str)
return nil, errors.bad_request(("lvalue is not a number for operation %s"):format(op_str))
end
if r_type == "string" then
rval = tonumber(rval)
if rval == nil then
return nil, ("can not parse string rvalue as number for operation %s"):format(op_str)
return nil,
errors.bad_request(("can not parse string rvalue as number for operation %s"):format(op_str))
end
elseif r_type ~= "number" then
return nil, ("rvalue is not a number for operation %s"):format(op_str)
return nil, errors.bad_request(("rvalue is not a number for operation %s"):format(op_str))
end
elseif op_type == OPERATOR_TYPES.LOGICAL then
-- everything which is not null is a true boolean
Expand Down Expand Up @@ -539,10 +543,10 @@ local function exec_binary_op(op, lval, rval, op_str)

-- must be the same type
if l_type ~= r_type then
return nil, ("can not apply %s on types %s and %s"):format(op_str, l_type, r_type)
return nil, errors.bad_request(("can not apply %s on types %s and %s"):format(op_str, l_type, r_type))
end
else
return nil, ("unknown operator %s"):format(op_str)
return nil, errors.bad_request(("unknown operator %s"):format(op_str))
end

return OPERATORS_FN[op](lval, rval), nil
Expand All @@ -554,10 +558,10 @@ local function eval_ast(ast, obj)
-- Helper helper: evaluate variable expression inside abstract syntax tree
local function eval_var(expr, obj)
if obj == nil then
return nil, 'object is not set'
return nil, errors.bad_request('object is not set')
end
if type(obj) ~= "table" then
return nil, 'object is primitive'
return nil, errors.not_found('object is primitive')
end
for i = 2, #expr do
-- [1] is "var"
Expand All @@ -568,7 +572,7 @@ local function eval_ast(ast, obj)
member = type(member) == 'number' and member + 1 or member
obj = obj[member]
if is_nil(obj) then
return nil, 'object doesn\'t contain an object or attribute "' .. member .. '"'
return nil, errors.not_found('object doesn\'t contain an object or attribute "'.. member ..'"')
end
end
return obj
Expand All @@ -585,7 +589,10 @@ local function eval_ast(ast, obj)
local function eval_union(expr, obj)
local matches = {} -- [1] is "union"
for i = 2, #expr do
local result = eval_ast(expr[i], obj)
local result, err = eval_ast(expr[i], obj)
if err then
return nil, err
end
if type(result) == 'table' then
for _, j in ipairs(result) do
table.insert(matches, j)
Expand All @@ -599,16 +606,33 @@ local function eval_ast(ast, obj)

-- Helper helper: evaluate 'filter' expression inside abstract syntax tree
local function eval_filter(expr, obj)
return eval_ast(expr[2], obj) and true or false
local result, err = eval_ast(expr[2], obj)
if err then
if err:is_not_found() then
return false
end
return nil, err
end
return result and true or false
end

-- Helper helper: evaluate 'slice' expression inside abstract syntax tree
local function eval_slice(expr, obj)
local matches = {} -- [1] is "slice"
if #expr == 4 then
local from = tonumber(eval_ast(expr[2], obj))
local to = tonumber(eval_ast(expr[3], obj))
local step = tonumber(eval_ast(expr[4], obj))
local from_result, err = eval_ast(expr[2], obj)
if err then return nil, err end

local to_result, err = eval_ast(expr[3], obj)
if err then return nil, err end

local step_result, err = eval_ast(expr[4], obj)
if err then return nil, err end

local from = tonumber(from_result)
local to = tonumber(to_result)
local step = tonumber(step_result)

if (from == nil) or (from < 0) or (to == nil) or (to < 0) then
local len = eval_var_length(obj)
if from == nil then
Expand Down Expand Up @@ -638,15 +662,15 @@ local function eval_ast(ast, obj)
for i = 3, #expr, 2 do
local op_str = expr[i]
if op_str == nil then
return nil, 'missing expression operator'
return nil, errors.bad_request('missing expression operator')
end
local op2, eval_err = eval_ast(expr[i + 1], obj)
if is_nil(op2) then
return nil, eval_err
end
local op = parse_operator(op_str)
if op == 0 then
return nil, "unknown operator"
return nil, errors.bad_request("unknown operator")
end
--- @cast op Operator
local result, cast_err = exec_binary_op(op, op1, op2, op_str)
Expand All @@ -672,8 +696,7 @@ local function eval_ast(ast, obj)
elseif ast[1] == 'filter' then
return eval_filter(ast, obj)
elseif ast[1] == 'slice' then
local result = eval_slice(ast, obj)
return result
return eval_slice(ast, obj)
end

return 0
Expand Down Expand Up @@ -705,7 +728,10 @@ local function match_path(ast, path, parent, obj)
end
elseif ast_spec[1] == 'union' or ast_spec[1] == 'slice' then
-- match union or slice expression (on parent object)
local matches = eval_ast(ast_spec, parent)
local matches, err = eval_ast(ast_spec, parent)
if err then
return nil, err
end
--- @cast matches table[]
for _, i in pairs(matches) do
match_component = tostring(i) == tostring(component)
Expand All @@ -715,7 +741,16 @@ local function match_path(ast, path, parent, obj)
end
elseif ast_spec[1] == 'filter' then
-- match filter expression
match_component = eval_ast(ast_spec, obj) and true or false
local filter_result, err = eval_ast(ast_spec, obj)
if err then
if err:is_not_found() then
match_component = false
else
return nil, err
end
else
match_component = filter_result and true or false
end
end
else
if ast_spec == '*' then
Expand All @@ -734,7 +769,16 @@ local function match_path(ast, path, parent, obj)
if path_index == #path and ast_spec ~= "array" and match_component then
local _, next_ast_spec = next(ast, ast_key)
if next_ast_spec ~= nil and next_ast_spec[1] == 'filter' then
match_component = eval_ast(next_ast_spec, obj) and true or false
local filter_result, err = eval_ast(next_ast_spec, obj)
if err then
if err:is_not_found() then
match_component = false
else
return nil, err
end
else
match_component = filter_result and true or false
end
ast_key, ast_spec = ast_iter(ast, ast_key)
end
end
Expand Down Expand Up @@ -769,7 +813,10 @@ end

local function match_tree(nodes, ast, path, parent, obj, count)
-- Try to match every node against AST
local match = match_path(ast, path, parent, obj)
local match, err = match_path(ast, path, parent, obj)
if err then
return err
end
if match == MATCH_ONE or match == MATCH_DESCENDANTS then
-- This node matches. Add path and value to result
-- (if max result count not yet reached)
Expand All @@ -792,7 +839,10 @@ local function match_tree(nodes, ast, path, parent, obj, count)
table.insert(path1, p)
end
table.insert(path1, type(key) == 'string' and key or (key - 1))
match_tree(nodes, ast, path1, obj, child, count)
local err = match_tree(nodes, ast, path1, obj, child, count)
if err then
return err
end
end
end
end
Expand All @@ -818,15 +868,15 @@ end
--
function M.parse(expr)
if expr == nil or type(expr) ~= 'string' then
return nil, "missing or invalid 'expr' argument"
return nil, errors.bad_request("missing or invalid 'expr' argument")
end

local ast = Ct(jsonpath_grammer * Cp()):match(expr)
if ast == nil or #ast ~= 2 then
return nil, 'invalid expression "' .. expr .. '"'
return nil, errors.bad_request('invalid expression "' .. expr .. '"')
end
if ast[2] ~= #expr + 1 then
return nil, 'invalid expression "' .. expr .. '" near "' .. expr:sub(ast[2]) .. '"'
return nil, errors.bad_request('invalid expression "' .. expr .. '" near "' .. expr:sub(ast[2]) .. '"')
end
return ast[1]
end
Expand All @@ -850,13 +900,13 @@ end
--
function M.nodes(obj, expr, count)
if obj == nil or type(obj) ~= 'table' then
return nil, "missing or invalid 'obj' argument"
return nil, errors.bad_request("missing or invalid 'obj' argument")
end
if expr == nil or (type(expr) ~= 'string' and type(expr) ~= 'table') then
return nil, "missing or invalid 'expr' argument"
return nil, errors.bad_request("missing or invalid 'expr' argument")
end
if count ~= nil and type(count) ~= 'number' then
return nil, "invalid 'count' argument"
return nil, errors.bad_request("invalid 'count' argument")
end

local ast, err
Expand All @@ -868,7 +918,10 @@ function M.nodes(obj, expr, count)
ast = expr
end
if ast == nil then
return nil, err or 'internal error'
if not err then
err = errors.internal("internal error")
end
return nil, err
end

if count ~= nil and count == 0 then
Expand All @@ -885,8 +938,10 @@ function M.nodes(obj, expr, count)
end

local matches = {}
match_tree(matches, ast, { '$' }, {}, obj, count)

local err = match_tree(matches, ast, { '$' }, {}, obj, count)
if err then
return nil, err
end
-- Sort results by path
local sorted = {}
for p, v in pairs(matches) do
Expand Down Expand Up @@ -938,7 +993,7 @@ function M.value(obj, expr, count)
return nodes[1].value
end

return nil, 'no element matching expression'
return nil, errors.bad_request('no element matching expression')
end


Expand Down
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