jimbaker/vdomtag.py

## vdomtag.py
# Don't name this file html.py

from __future__ import annotations

from functools import cache
from types import CodeType
from typing import *
from html.parser import HTMLParser

from viewdom import VDOMNode, render

# getvalue, raw, conv, formatspec
Thunk = tuple[
    Callable[[], Any],
    str,
    str | None,
    str | None,
]

class VdomCodeBuilder(HTMLParser):
    """Given HTML input with interpolation, builds source code to construct equivalent vdom"""
    def __init__(self):
        self.lines = ['def compiled(vdom, /, *args):', '  return \\']
        self.tag_stack = []
        super().__init__()

    def indent(self) -> str:
        return '  ' * (len(self.tag_stack) + 2)

    @property
    def code(self) -> str:
        return '\n'.join(self.lines)

    def handle_starttag(self, tag, attrs):
        self.lines.append(f"{self.indent()}vdom('{tag}', {dict(attrs)!r}, [")
        self.tag_stack.append(tag)

    def handle_endtag(self, tag):
        if tag != self.tag_stack[-1]:
            raise RuntimeError(f"unexpected </{tag}>")
        self.tag_stack.pop()
        self.lines.append(f'{self.indent()}]){"," if self.tag_stack else ""}')

    def handle_data(self, data: str):
        # At the very least the first empty line needs to be removed, as might
        # be seen in
        # html"""
        #   <tag>..</tag>
        # """
        # (given that our codegen is so rudimentary!)

        # Arguably other blank strings should be removed as well, and this
        # stripping results in having output equivalent to standard vdom
        # construction.
        if not data.strip():
            return
        self.lines.append(f'{self.indent()}{data!r},')

    def add_interpolation(self, i: int):
        # Call getvalue for the thunk at the i-th position in args. This
        # interpolation could optionally also process formatspec, conversion.
        self.lines.append(f'{self.indent()}args[{i}][0](), ')

@cache
def make_compiled_template(*args: str | CodeType) -> Callable:
    print(f'Making compiled template {hash(args)}...')
    builder = VdomCodeBuilder()
    for i, arg in enumerate(args):
        if isinstance(arg, str):
            builder.feed(arg)
        else:
            # NOTE: Use a code object to represent the function interpolation.
            # However, we are just passing in the argument position, so it's
            # reasonable.
            builder.add_interpolation(i)
    print(builder.code)
    code_obj = compile(builder.code, '<string>', 'exec')
    captured = {}
    exec(code_obj, captured)
    return captured['compiled']

# The "lambda wrappers" function object will change at each usage of the call
# site. Let's use the underlying code object instead as part of the key to
# construct the compiled function so it can be memoized. This approach is
# correct, since we will call getvalue in the thunk in the interpolation.

def immutable_bits(*args: str | Thunk) -> Tuple(str | CodeType):
    bits = []
    for arg in args:
        if isinstance(arg, str):
            bits.append(arg)
        else:
            bits.append((arg[0].__code__,))
    return tuple(bits)

# This is the actual 'tag' function: html"<body>blah</body>"

def html(*args: str | Thunk) -> VdomDict:
    compiled = make_compiled_template(*immutable_bits(*args))
    return compiled(VDOMNode, *args)

def useit():
    for i in range(3):
        for j in range(3):
            node = html'<body attr1=47><div>{i} along with {j}</div></body>'
            print(node)
            print(render(node))

if __name__ == '__main__':
    useit()
	# Don't name this file html.py

	from __future__ import annotations

	from functools import cache
	from types import CodeType
	from typing import *
	from html.parser import HTMLParser

	from viewdom import VDOMNode, render

	# getvalue, raw, conv, formatspec
	Thunk = tuple[
	Callable[[], Any],
	str,
	str \| None,
	str \| None,
	]

	class VdomCodeBuilder(HTMLParser):
	"""Given HTML input with interpolation, builds source code to construct equivalent vdom"""
	def __init__(self):
	self.lines = ['def compiled(vdom, /, *args):', ' return \\']
	self.tag_stack = []
	super().__init__()

	def indent(self) -> str:
	return ' ' * (len(self.tag_stack) + 2)

	@property
	def code(self) -> str:
	return '\n'.join(self.lines)

	def handle_starttag(self, tag, attrs):
	self.lines.append(f"{self.indent()}vdom('{tag}', {dict(attrs)!r}, [")
	self.tag_stack.append(tag)

	def handle_endtag(self, tag):
	if tag != self.tag_stack[-1]:
	raise RuntimeError(f"unexpected </{tag}>")
	self.tag_stack.pop()
	self.lines.append(f'{self.indent()}]){"," if self.tag_stack else ""}')

	def handle_data(self, data: str):
	# At the very least the first empty line needs to be removed, as might
	# be seen in
	# html"""
	# <tag>..</tag>
	# """
	# (given that our codegen is so rudimentary!)

	# Arguably other blank strings should be removed as well, and this
	# stripping results in having output equivalent to standard vdom
	# construction.
	if not data.strip():
	return
	self.lines.append(f'{self.indent()}{data!r},')

	def add_interpolation(self, i: int):
	# Call getvalue for the thunk at the i-th position in args. This
	# interpolation could optionally also process formatspec, conversion.
	self.lines.append(f'{self.indent()}args[{i}][0](), ')

	@cache
	def make_compiled_template(*args: str \| CodeType) -> Callable:
	print(f'Making compiled template {hash(args)}...')
	builder = VdomCodeBuilder()
	for i, arg in enumerate(args):
	if isinstance(arg, str):
	builder.feed(arg)
	else:
	# NOTE: Use a code object to represent the function interpolation.
	# However, we are just passing in the argument position, so it's
	# reasonable.
	builder.add_interpolation(i)
	print(builder.code)
	code_obj = compile(builder.code, '<string>', 'exec')
	captured = {}
	exec(code_obj, captured)
	return captured['compiled']

	# The "lambda wrappers" function object will change at each usage of the call
	# site. Let's use the underlying code object instead as part of the key to
	# construct the compiled function so it can be memoized. This approach is
	# correct, since we will call getvalue in the thunk in the interpolation.

	def immutable_bits(*args: str \| Thunk) -> Tuple(str \| CodeType):
	bits = []
	for arg in args:
	if isinstance(arg, str):
	bits.append(arg)
	else:
	bits.append((arg[0].__code__,))
	return tuple(bits)

	# This is the actual 'tag' function: html"<body>blah</body>"

	def html(*args: str \| Thunk) -> VdomDict:
	compiled = make_compiled_template(immutable_bits(args))
	return compiled(VDOMNode, *args)

	def useit():
	for i in range(3):
	for j in range(3):
	node = html'<body attr1=47><div>{i} along with {j}</div></body>'
	print(node)
	print(render(node))

	if __name__ == '__main__':
	useit()