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+-- Copyright (C) 2021 Kim Alvefur
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+-- Based on
+-- https://json-schema.org/draft/2020-12/json-schema-core.html
+-- https://json-schema.org/draft/2020-12/json-schema-validation.html
+-- http://spec.openapis.org/oas/v3.0.1#xmlObject
+-- https://github.com/OAI/OpenAPI-Specification/issues/630 (text:true)
+--
+-- XML Object Extensions:
+-- text to refer to the text content at the same time as attributes
+-- x_name_is_value for enum fields where the <tag-name/> is the value
+-- x_single_attribute for <tag attr="this"/>
+--
+-- TODO pointers
+-- TODO cleanup / refactor
+-- TODO s/number/integer/ once we have appropriate math.type() compat
+--
+
+local st = require "util.stanza";
+local json = require"util.json"
+
+local json_type_name = json.json_type_name;
+local json_schema_object = require "util.jsonschema"
+local type schema_t = boolean | json_type_name | json_schema_object
+
+local function toboolean ( s : string ) : boolean
+ if s == "true" or s == "1" then
+ return true
+ elseif s == "false" or s == "0" then
+ return false
+ elseif s then
+ return true
+ end
+end
+
+local function totype(t : json_type_name, s : string) : any
+ if not s then return nil end
+ if t == "string" then
+ return s;
+ elseif t == "boolean" then
+ return toboolean(s)
+ elseif t == "number" or t == "integer" then
+ return tonumber(s)
+ end
+end
+
+local enum value_goes
+ "in_tag_name"
+ "in_text"
+ "in_text_tag"
+ "in_attribute"
+ "in_single_attribute"
+ "in_children"
+ "in_wrapper"
+end
+
+local function unpack_propschema( propschema : schema_t, propname : string, current_ns : string )
+ : json_type_name, value_goes, string, string, string, string, { any }
+ local proptype : json_type_name = "string"
+ local value_where : value_goes = propname and "in_text_tag" or "in_text"
+ local name = propname
+ local namespace : string
+ local prefix : string
+ local single_attribute : string
+ local enums : { any }
+
+ if propschema is json_schema_object then
+ proptype = propschema.type
+ elseif propschema is json_type_name then
+ proptype = propschema
+ end
+
+ if proptype == "object" or proptype == "array" then
+ value_where = "in_children"
+ end
+
+ if propschema is json_schema_object then
+ local xml = propschema.xml
+ if xml then
+ if xml.name then
+ name = xml.name
+ end
+ if xml.namespace and xml.namespace ~= current_ns then
+ namespace = xml.namespace
+ end
+ if xml.prefix then
+ prefix = xml.prefix
+ end
+ if proptype == "array" and xml.wrapped then
+ value_where = "in_wrapper"
+ elseif xml.attribute then
+ value_where = "in_attribute"
+ elseif xml.text then
+ value_where = "in_text"
+ elseif xml.x_name_is_value then
+ value_where = "in_tag_name"
+ elseif xml.x_single_attribute then
+ single_attribute = xml.x_single_attribute
+ value_where = "in_single_attribute"
+ end
+ end
+ if propschema["const"] then
+ enums = { propschema["const"] }
+ elseif propschema["enum"] then
+ enums = propschema["enum"]
+ end
+ end
+
+ return proptype, value_where, name, namespace, prefix, single_attribute, enums
+end
+
+local parse_object : function (schema : schema_t, s : st.stanza_t) : { string : any }
+local parse_array : function (schema : schema_t, s : st.stanza_t) : { any }
+
+local function extract_value (s : st.stanza_t, value_where : value_goes, proptype : json.json_type_name, name : string, namespace : string, prefix : string, single_attribute : string, enums : { any }) : string
+ if value_where == "in_tag_name" then
+ local c : st.stanza_t
+ if proptype == "boolean" then
+ c = s:get_child(name, namespace);
+ elseif enums and proptype == "string" then
+ -- XXX O(n²) ?
+ -- Probably better to flip the table and loop over :childtags(nil, ns), should be 2xO(n)
+ -- BUT works first, optimize later
+ for i = 1, #enums do
+ c = s:get_child(enums[i] as string, namespace);
+ if c then break end
+ end
+ else
+ c = s:get_child(nil, namespace);
+ end
+ if c then
+ return c.name;
+ end
+ elseif value_where == "in_attribute" then
+ local attr = name
+ if prefix then
+ attr = prefix .. ':' .. name
+ elseif namespace and namespace ~= s.attr.xmlns then
+ attr = namespace .. "\1" .. name
+ end
+ return s.attr[attr]
+
+ elseif value_where == "in_text" then
+ return s:get_text()
+
+ elseif value_where == "in_single_attribute" then
+ local c = s:get_child(name, namespace)
+ return c and c.attr[single_attribute]
+ elseif value_where == "in_text_tag" then
+ return s:get_child_text(name, namespace)
+ end
+end
+
+function parse_object (schema : schema_t, s : st.stanza_t) : { string : any }
+ local out : { string : any } = {}
+ if schema is json_schema_object and schema.properties then
+ for prop, propschema in pairs(schema.properties) do
+
+ local proptype, value_where, name, namespace, prefix, single_attribute, enums = unpack_propschema(propschema, prop, s.attr.xmlns)
+
+ if value_where == "in_children" and propschema is json_schema_object then
+ if proptype == "object" then
+ local c = s:get_child(name, namespace)
+ if c then
+ out[prop] = parse_object(propschema, c);
+ end
+ elseif proptype == "array" then
+ local a = parse_array(propschema, s);
+ if a and a[1] ~= nil then
+ out[prop] = a;
+ end
+ else
+ error "unreachable"
+ end
+ elseif value_where == "in_wrapper" and propschema is json_schema_object and proptype == "array" then
+ local wrapper = s:get_child(name, namespace);
+ if wrapper then
+ out[prop] = parse_array(propschema, wrapper);
+ end
+ else
+ local value : string = extract_value (s, value_where, proptype, name, namespace, prefix, single_attribute, enums)
+
+ out[prop] = totype(proptype, value)
+ end
+ end
+ end
+
+ return out
+end
+
+function parse_array (schema : json_schema_object, s : st.stanza_t) : { any }
+ local itemschema : schema_t = schema.items;
+ local proptype, value_where, child_name, namespace, prefix, single_attribute, enums = unpack_propschema(itemschema, nil, s.attr.xmlns)
+ local attr_name : string
+ if value_where == "in_single_attribute" then -- FIXME this shouldn't be needed
+ value_where = "in_attribute";
+ attr_name = single_attribute;
+ end
+ local out : { any } = {}
+
+ if proptype == "object" then
+ if itemschema is json_schema_object then
+ for c in s:childtags(child_name, namespace) do
+ table.insert(out, parse_object(itemschema, c));
+ end
+ else
+ error "array items must be schema object"
+ end
+ elseif proptype == "array" then
+ if itemschema is json_schema_object then
+ for c in s:childtags(child_name, namespace) do
+ table.insert(out, parse_array(itemschema, c));
+ end
+ end
+ else
+ for c in s:childtags(child_name, namespace) do
+ local value : string = extract_value (c, value_where, proptype, attr_name or child_name, namespace, prefix, single_attribute, enums)
+
+ table.insert(out, totype(proptype, value));
+ end
+ end
+ return out;
+end
+
+local function parse (schema : json_schema_object, s : st.stanza_t) : table
+ if schema.type == "object" then
+ return parse_object(schema, s)
+ elseif schema.type == "array" then
+ return parse_array(schema, s)
+ else
+ error "top-level scalars unsupported"
+ end
+end
+
+local function toxmlstring(proptype : json_type_name, v : any) : string
+ if proptype == "string" and v is string then
+ return v
+ elseif proptype == "number" and v is number then
+ return string.format("%g", v)
+ elseif proptype == "integer" and v is number then -- TODO is integer
+ return string.format("%d", v)
+ elseif proptype == "boolean" then
+ return v and "1" or "0"
+ end
+end
+
+local unparse : function (json_schema_object, table, string, string, st.stanza_t) : st.stanza_t
+
+local function unparse_property(out : st.stanza_t, v : any, proptype : json_type_name, propschema : schema_t, value_where : value_goes, name : string, namespace : string, current_ns : string, prefix : string, single_attribute : string)
+ if value_where == "in_attribute" then
+ local attr = name
+ if prefix then
+ attr = prefix .. ':' .. name
+ elseif namespace and namespace ~= current_ns then
+ attr = namespace .. "\1" .. name
+ end
+
+ out.attr[attr] = toxmlstring(proptype, v)
+ elseif value_where == "in_text" then
+ out:text(toxmlstring(proptype, v))
+ elseif value_where == "in_single_attribute" then
+ assert(single_attribute)
+ local propattr : { string : string } = {}
+
+ if namespace and namespace ~= current_ns then
+ propattr.xmlns = namespace
+ end
+
+ propattr[single_attribute] = toxmlstring(proptype, v)
+ out:tag(name, propattr):up();
+
+ else
+ local propattr : { string : string }
+ if namespace ~= current_ns then
+ propattr = { xmlns = namespace }
+ end
+ if value_where == "in_tag_name" then
+ if proptype == "string" and v is string then
+ out:tag(v, propattr):up();
+ elseif proptype == "boolean" and v == true then
+ out:tag(name, propattr):up();
+ end
+ elseif proptype == "object" and propschema is json_schema_object and v is table then
+ local c = unparse(propschema, v, name, namespace);
+ if c then
+ out:add_direct_child(c);
+ end
+ elseif proptype == "array" and propschema is json_schema_object and v is table then
+ if value_where == "in_wrapper" then
+ local c = unparse(propschema, v, name, namespace);
+ if c then
+ out:add_direct_child(c);
+ end
+ else
+ unparse(propschema, v, name, namespace, out);
+ end
+ else
+ out:text_tag(name, toxmlstring(proptype, v), propattr)
+ end
+ end
+end
+
+function unparse ( schema : json_schema_object, t : table, current_name : string, current_ns : string, ctx : st.stanza_t ) : st.stanza_t
+
+ if schema.xml then
+ if schema.xml.name then
+ current_name = schema.xml.name
+ end
+ if schema.xml.namespace then
+ current_ns = schema.xml.namespace
+ end
+ -- TODO prefix?
+ end
+
+ local out = ctx or st.stanza(current_name, { xmlns = current_ns })
+
+ if schema.type == "object" then
+
+ for prop, propschema in pairs(schema.properties) do
+ local v = t[prop]
+
+ if v ~= nil then
+ local proptype, value_where, name, namespace, prefix, single_attribute = unpack_propschema(propschema, prop, current_ns)
+ unparse_property(out, v, proptype, propschema, value_where, name, namespace, current_ns, prefix, single_attribute)
+ end
+ end
+ return out;
+
+ elseif schema.type == "array" then
+ local proptype, value_where, name, namespace, prefix, single_attribute = unpack_propschema(schema.items, current_name, current_ns)
+ for _, item in ipairs(t as { string }) do
+ unparse_property(out, item, proptype, schema.items, value_where, name, namespace, current_ns, prefix, single_attribute)
+ end
+ return out;
+ end
+end
+
+return {
+ parse = parse,
+ unparse = unparse,
+}