A tool in jerry-ext: arg transformer for binding (#1740)

It provides some APIs for binding developers, so that they can validate the type of the js argument and convert/assign them to the native argument. Related Issue: #1716 JerryScript-DCO-1.0-Signed-off-by: Martijn The martijn.the@intel.com JerryScript-DCO-1.0-Signed-off-by: Zidong Jiang zidong.jiang@intel.com
2017-05-04 18:00:35 +08:00
parent ede13835b2
commit 90efdf9c8b
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+# jerryx_arg types
+
+## jerryx_arg_t
+
+**Summary**
+
+The structure defining a single validation/transformation step.
+
+*Note*: For commonly used validators, `arg.h` provides helpers to create the `jerryx_arg_t`s.
+For example, `jerryx_arg_number ()`, `jerryx_arg_boolean ()`, etc.
+
+**Prototype**
+
+```c
+typedef struct
+{
+  /** the transform function */
+  jerryx_arg_transform_func_t func;
+  /** pointer to destination where func should store the result */
+  void *dest;
+  /** extra information, specific to func */
+  uintptr_t extra_info;
+} jerryx_arg_t;
+```
+
+**See also**
+
+- [jerryx_arg_number](#jerryx_arg_number)
+- [jerryx_arg_boolean](#jerryx_arg_boolean)
+- [jerryx_arg_string](#jerryx_arg_string)
+- [jerryx_arg_function](#jerryx_arg_function)
+- [jerryx_arg_native_pointer](#jerryx_arg_native_pointer)
+- [jerryx_arg_ignore](#jerryx_arg_ignore)
+
+## jerryx_arg_transform_func_t
+
+**Summary**
+
+Signature of the transform function.
+
+Users can create custom transformations by implementing a transform function
+and using `jerryx_arg_custom ()`.
+
+The function is expected to return `undefined` if it ran successfully or
+return an `Error` in case it failed. The function can use the iterator and the
+helpers `jerryx_arg_js_iterator_pop ()` and `jerryx_arg_js_iterator_peek ()` to
+get the next input value.
+
+*Note*: A transform function is allowed to consume any number of input values!
+This enables complex validation like handling different JS function signatures,
+mapping multiple input arguments to a C struct, etc.
+
+The function is expected to store the result of
+a successful transformation into `c_arg_p->dest`. In case the validation did
+not pass, the transform should not modify `c_arg_p->dest`.
+
+Additional parameters can be provided to the function through `c_arg_p->extra_info`.
+
+**Prototype**
+
+```c
+typedef jerry_value_t (*jerryx_arg_transform_func_t) (jerryx_arg_js_iterator_t *js_arg_iter_p,
+                                                      const jerryx_arg_t *c_arg_p);
+```
+
+**See also**
+
+- [jerryx_arg_custom](#jerryx_arg_custom)
+- [jerryx_arg_js_iterator_pop](#jerryx_arg_js_iterator_pop)
+- [jerryx_arg_js_iterator_peek](#jerryx_arg_js_iterator_peek)
+
+
+## jerryx_arg_coerce_t
+
+Enum that indicates whether an argument is allowed to be coerced into the expected JS type.
+
+ - JERRYX_ARG_COERCE - the transform will invoke toNumber, toBoolean, toString, etc.
+ - JERRYX_ARG_NO_COERCE - the type coercion is not allowed. The transform will fail if the type does not match the expectation.
+
+**See also**
+
+- [jerryx_arg_number](#jerryx_arg_number)
+- [jerryx_arg_boolean](#jerryx_arg_boolean)
+- [jerryx_arg_string](#jerryx_arg_string)
+
+## jerryx_arg_optional_t
+
+Enum that indicates whether an argument is optional or required.
+
+ - JERRYX_ARG_OPTIONAL - The argument is optional. If the argument is `undefined` the transform is successful and `c_arg_p->dest` remains untouched.
+ - JERRYX_ARG_REQUIRED - The argument is required. If the argument is `undefined` the transform will fail and `c_arg_p->dest` remains untouched.
+
+**See also**
+
+- [jerryx_arg_number](#jerryx_arg_number)
+- [jerryx_arg_boolean](#jerryx_arg_boolean)
+- [jerryx_arg_string](#jerryx_arg_string)
+- [jerryx_arg_function](#jerryx_arg_function)
+- [jerryx_arg_native_pointer](#jerryx_arg_native_pointer)
+
+# Main functions
+
+## jerryx_arg_transform_this_and_args
+
+**Summary**
+
+Validate the this value and the JS arguments, and assign them to the native arguments.
+This function is useful to perform input validation inside external function handlers (see `jerry_external_handler_t`).
+
+**Prototype**
+
+```c
+jerry_value_t
+jerryx_arg_transform_this_and_args (const jerry_value_t this_val,
+                                    const jerry_value_t *js_arg_p,
+                                    const jerry_length_t js_arg_cnt,
+                                    const jerryx_arg_t *c_arg_p,
+                                    jerry_length_t c_arg_cnt)
+```
+
+ - `this_val` - `this` value. Note this is processed as the first value, before the array of arguments.
+ - `js_arg_p` - points to the array with JS arguments.
+ - `js_arg_cnt` - the count of the `js_arg_p` array.
+ - `c_arg_p` - points to the array of validation/transformation steps
+ - `c_arg_cnt` - the count of the `c_arg_p` array.
+ - return value - a `jerry_value_t` representing `undefined` if all validators passed or an `Error` if a validator failed.
+
+**Example**
+
+```c
+// JS signature: function (requiredBool, requiredString, optionalNumber)
+static jerry_value_t my_external_handler (const jerry_value_t function_obj,
+                                          const jerry_value_t this_val,
+                                          const jerry_value_t args_p[],
+                                          const jerry_length_t args_count)
+{
+  bool required_bool;
+  char required_str[16];
+  double optional_num = 1234.567;  // default value
+
+  // "mapping" defines the steps to transform input arguments to C variables:
+  const jerryx_arg_t mapping[] =
+  {
+    // `this` is the first value. No checking needed on `this` for this function.
+    jerryx_arg_ignore (),
+
+    jerryx_arg_boolean (&required_bool, JERRYX_ARG_NO_COERCE, JERRYX_ARG_REQUIRED),
+    jerryx_arg_string (&required_str, sizeof (required_str), JERRYX_ARG_NO_COERCE, JERRYX_ARG_REQUIRED),
+    jerryx_arg_number (&optional_num, JERRYX_ARG_NO_COERCE, JERRYX_ARG_OPTIONAL),
+  };
+
+  // Validate and transform:
+  const jerry_value_t rv = jerryx_arg_transform_this_and_args (this_val,
+                                                               args_p,
+                                                               args_count,
+                                                               mapping,
+                                                               ARRAY_LENGTH (mapping));
+
+  if (jerry_value_has_error_flag (rv))
+  {
+    // Handle error
+    return rv;
+  }
+
+  // Validated and tranformed successfully!
+  // required_bool, required_str and optional_num can now be used.
+  // ...
+}
+```
+
+**See also**
+
+- [jerryx_arg_ignore](#jerryx_arg_ignore)
+- [jerryx_arg_number](#jerryx_arg_number)
+- [jerryx_arg_boolean](#jerryx_arg_boolean)
+- [jerryx_arg_string](#jerryx_arg_string)
+- [jerryx_arg_function](#jerryx_arg_function)
+- [jerryx_arg_native_pointer](#jerryx_arg_native_pointer)
+- [jerryx_arg_custom](#jerryx_arg_custom)
+
+
+## jerryx_arg_transform_args
+
+**Summary**
+
+Validate an array of `jerry_value_t` and assign them to the native arguments.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerryx_arg_transform_args (const jerry_value_t *js_arg_p,
+                           const jerry_length_t js_arg_cnt,
+                           const jerryx_arg_t *c_arg_p,
+                           jerry_length_t c_arg_cnt)
+```
+
+ - `js_arg_p` - points to the array with JS arguments.
+ - `js_arg_cnt` - the count of the `js_arg_p` array.
+ - `c_arg_p` - points to the array of validation/transformation steps
+ - `c_arg_cnt` - the count of the `c_arg_p` array.
+ - return value - a `jerry_value_t` representing `undefined` if all validators passed or an `Error` if a validator failed.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+
+# Helpers for commonly used validations
+
+## jerryx_arg_number
+
+**Summary**
+
+Create a validation/transformation step (`jerryx_arg_t`) that expects to consume
+one `number` JS argument and stores it into a C `double`.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_number (double *dest,
+                   jerryx_arg_coerce_t coerce_flag,
+                   jerryx_arg_optional_t opt_flag)
+```
+
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to the `double` where the result should be stored.
+ - `coerce_flag` - whether type coercion is allowed.
+ - `opt_flag` - whether the argument is optional.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+## jerryx_arg_boolean
+
+**Summary**
+
+Create a validation/transformation step (`jerryx_arg_t`) that expects to
+consume one `boolean` JS argument and stores it into a C `bool`.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_boolean (bool *dest,
+                    jerryx_arg_coerce_t coerce_flag,
+                    jerryx_arg_optional_t opt_flag)
+```
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to the `bool` where the result should be stored.
+ - `coerce_flag` - whether type coercion is allowed.
+ - `opt_flag` - whether the argument is optional.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+
+## jerryx_arg_string
+
+**Summary**
+
+Create a validation/transformation step (`jerryx_arg_t`) that expects to
+consume one `string` JS argument and stores it into a C `char` array.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_string (char *dest,
+                   uint32_t size,
+                   jerryx_arg_coerce_t coerce_flag,
+                   jerryx_arg_optional_t opt_flag)
+```
+
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to the native char array where the result should be stored.
+ - `size` - the size of native char array.
+ - `coerce_flag` - whether type coercion is allowed.
+ - `opt_flag` - whether the argument is optional.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+
+## jerryx_arg_function
+
+**Summary**
+
+Create a validation/transformation step (`jerryx_arg_t`) that expects to
+consume one `function` JS argument and stores it into a C `jerry_value_t`.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_function (jerry_value_t *dest,
+                     jerryx_arg_optional_t opt_flag)
+
+```
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to the `jerry_value_t` where the result should be stored.
+ - `opt_flag` - whether the argument is optional.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+## jerryx_arg_native_pointer
+
+**Summary**
+
+Create a validation/transformation step (`jerryx_arg_t`) that expects to
+consume one `Object` JS argument that is 'backed' with a native pointer with
+a given type info. In case the native pointer info matches, the transform
+will succeed and the object's native pointer will be assigned to `*dest`.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_native_pointer (void **dest,
+                           const jerry_object_native_info_t *info_p,
+                           jerryx_arg_optional_t opt_flag)
+```
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to where the resulting native pointer should be stored.
+ - `info_p` - expected the type info.
+ - `opt_flag` - whether the argument is optional.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+
+# Functions to create custom validations
+
+## jerryx_arg_custom
+
+**Summary**
+
+Create a jerryx_arg_t instance with custom transform.
+
+**Prototype**
+
+```c
+static inline jerryx_arg_t
+jerryx_arg_custom (void *dest,
+                   uintptr_t extra_info,
+                   jerryx_arg_transform_func_t func)
+
+```
+ - return value - the created `jerryx_arg_t` instance.
+ - `dest` - pointer to the native argument where the result should be stored.
+ - `extra_info` - the extra parameter data, specific to the transform function.
+ - `func` - the custom transform function.
+
+**See also**
+
+- [jerryx_arg_transform_this_and_args](#jerryx_arg_transform_this_and_args)
+
+
+
+## jerryx_arg_js_iterator_pop
+
+**Summary**
+
+Pop the current `jerry_value_t` argument from the iterator.
+It will change the `js_arg_idx` and `js_arg_p` value in the iterator.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerryx_arg_js_iterator_pop (jerryx_arg_js_iterator_t *js_arg_iter_p)
+```
+ - return value - the `jerry_value_t` argument that was popped.
+ - `js_arg_iter_p` - the JS arg iterator from which to pop.
+
+## jerryx_arg_js_iterator_peek
+
+**Summary**
+
+Get the current JS argument from the iterator, without moving the iterator forward.
+*Note:* Unlike `jerryx_arg_js_iterator_pop ()`, it will not change `js_arg_idx` and
+`js_arg_p` value in the iterator.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerryx_arg_js_iterator_peek (jerryx_arg_js_iterator_t *js_arg_iter_p)
+```
+ - return value - the current `jerry_value_t` argument.
+ - `js_arg_iter_p` - the JS arg iterator from which to peek.
+
+## jerryx_arg_js_iterator_index
+
+**Summary**
+
+Get the index of the current JS argument from the iterator.
+
+**Prototype**
+
+```c
+jerry_length_t
+jerryx_arg_js_iterator_index (jerryx_arg_js_iterator_t *js_arg_iter_p)
+```
+ - return value - the index of current JS argument.
+ - `js_arg_iter_p` - the JS arg iterator from which to peek.