Source code for panel.models.reactive_html

import difflib
import re

from collections import defaultdict
from html.parser import HTMLParser

import as bp

from import ModelEvent
from bokeh.model import DataModel
from bokeh.models import LayoutDOM

from .layout import HTMLBox

endfor = '{%-? endfor -?%}'
list_iter_re = r'{%-? for (\s*[A-Za-z_]\w*\s*) in (\s*[A-Za-z_]\w*\s*) -?%}'
items_iter_re = r'{%-? for \s*[A-Za-z_]\w*\s*, (\s*[A-Za-z_]\w*\s*) in (\s*[A-Za-z_]\w*\s*)\.items\(\) -?%}'
values_iter_re = r'{%-? for (\s*[A-Za-z_]\w*\s*) in (\s*[A-Za-z_]\w*\s*)\.values\(\) -?%}'

[docs]class ReactiveHTMLParser(HTMLParser): def __init__(self, cls, template=True): super().__init__() self.template = template self.cls = cls self.attrs = defaultdict(list) self.children = {} self.nodes = [] self.looped = [] self._template_re = re.compile(r'\$\{[^}]+\}') self._literal_re = re.compile(r'\{\{[^}]+\}\}') self._current_node = None self._node_stack = [] self._open_for = False self.loop_map = {} self.loop_var_map = defaultdict(list) def handle_starttag(self, tag, attrs): attrs = dict(attrs) dom_id = attrs.pop('id', None) self._current_node = None self._node_stack.append((tag, dom_id)) if not dom_id: for attr, value in attrs.items(): if value is None: continue params, methods = [], [] for match in self._template_re.findall(value): match = match[2:-1] if match.startswith('model.'): continue if match in self.cls.param: params.append(match) elif hasattr(self.cls, match): methods.append(match) if methods: raise ValueError( "DOM nodes with an attached callback must declare " f"an id. Found <{tag}> node with the `{attr}` callback " f"referencing the `{methods[0]}` method. Add an id " "attribute like this: " f"<{tag} id=\"{tag}\" {attr}=\"${{{methods[0]}}}>...</{tag}>." ) elif params: literal = value.replace(f'${{{params[0]}}}', f'{{{{{params[0]}}}}}') raise ValueError( "DOM node with a linked parameter declaration " f"must declare an id. Found <{tag}> node with " f"the `{attr}` attribute referencing the `{params[0]}` " "parameter. Either declare an id on the node, " f"i.e. <{tag} id=\"{tag}\" {attr}=\"{value}\">...</{tag}>, " "or insert the value as a literal: " f"<{tag} {attr}=\"{literal}\">...</{tag}>." ) return if dom_id in self.nodes: raise ValueError(f'Multiple DOM nodes with id="{dom_id}" found.') self._current_node = dom_id self.nodes.append(dom_id) for attr, value in attrs.items(): if value is None: continue matches = [] for match in self._template_re.findall(value): if not match[2:-1].startswith('model.'): matches.append(match[2:-1]) if matches: self.attrs[dom_id].append((attr, matches, value.replace('${', '{'))) def handle_endtag(self, tag): self._node_stack.pop() self._current_node = self._node_stack[-1][1] if self._node_stack else None def handle_data(self, data): if not self.template: return dom_id = self._current_node matches = [] for match in self._template_re.findall(data): var = match[2:-1].strip() if match[2:-1] not in self.loop_var_map[var]: self.loop_var_map[var].append(match[2:-1]) if var.endswith('.index0'): matches.append('${%s }}]}' % var) else: matches.append('${%s}' % var) literal_matches = [] for match in self._literal_re.findall(data): match = match[2:-2].strip() if match.endswith('.index0'): literal_matches.append('{{%s }}]}' % match) else: literal_matches.append('{{ %s }}' % match) # Detect templating for loops list_loop = re.findall(list_iter_re, data) values_loop = re.findall(values_iter_re, data) items_loop = re.findall(items_iter_re, data) nloops = len(list_loop) + len(values_loop) + len(items_loop) if nloops > 1 and nloops and self._open_for: raise ValueError('Nested for loops currently not supported in templates.') elif nloops: loop = [loop for loop in (list_loop, values_loop, items_loop) if loop][0] var, obj = loop[0] if var in self.cls.param: raise ValueError( f'Loop variable {var} clashes with parameter name. ' 'Ensure loop variables have a unique name. Relevant ' f'template section:\n\n{data}' ) self.loop_map[var] = obj open_for ='{%-? for', data) end_for =, data) if open_for: if self._current_node is None: node = self._node_stack[-1][0] raise ValueError( 'Loops may only be used inside a DOM node with an assigned ID. ' f'The following loop could not be expanded because the <{node}> node ' f'did not have an assigned id:\n\n {data.strip()}' ) self._open_for = True if end_for and (not nloops or end_for.start() > open_for.start()): self._open_for = False if self._current_node and literal_matches: if len(literal_matches) == 1: literal_match = literal_matches[0][2:-2].strip() else: literal_match = None if literal_match and (literal_match in self.loop_map) and self._open_for: literal_match = self.loop_map[literal_match] self.looped.append((dom_id, literal_match)) if not (self._current_node and matches): return if len(matches) == 1: match = matches[0][2:-1].strip() else: for match in matches: mode = self.cls._child_config.get(match, 'model') if mode != 'template': raise ValueError(f"Cannot match multiple variables in '{mode}' mode.") match = None # Handle looped variables if match and (match.strip() in self.loop_map or '[' in match) and self._open_for: if match.strip() in self.loop_map: loop_match = self.loop_map[match.strip()] matches[matches.index('${%s}' % match)] = '${%s}' % loop_match match = loop_match elif '[' in match: match, _ = match.split('[') dom_id = dom_id.replace('-{{ loop.index0 }}', '') self.looped.append((dom_id, match)) mode = self.cls._child_config.get(match, 'model') if match in self.cls.param and mode != 'template': self.children[dom_id] = match return templates = [] for match in matches: match = match[2:-1] if match.startswith('model.'): continue if match not in self.cls.param and '.' not in match: params = difflib.get_close_matches(match, list(self.cls.param)) raise ValueError(f"{self.cls.__name__} HTML template references " f"unknown parameter '{match}', similar parameters " f"include {params}.") templates.append(match) self.attrs[dom_id].append(('children', templates, data.replace('${', '{')))
def find_attrs(html): p = ReactiveHTMLParser() p.feed(html) return p.attrs
[docs]class DOMEvent(ModelEvent): event_name = 'dom_event' def __init__(self, model, node=None, data=None): = data self.node = node super().__init__(model=model)
class ReactiveHTML(HTMLBox): attrs = bp.Dict(bp.String, bp.List(bp.Tuple(bp.String, bp.List(bp.String), bp.String))) callbacks = bp.Dict(bp.String, bp.List(bp.Tuple(bp.String, bp.String))) children = bp.Dict(bp.String, bp.Either(bp.List(bp.Either(bp.Instance(LayoutDOM), bp.String)), bp.String)) data = bp.Instance(DataModel) events = bp.Dict(bp.String, bp.Dict(bp.String, bp.Bool)) html = bp.String() looped = bp.List(bp.String) nodes = bp.List(bp.String) scripts = bp.Dict(bp.String, bp.List(bp.String)) def __init__(self, **props): if 'attrs' not in props and 'html' in props: props['attrs'] = find_attrs(props['html']) super().__init__(**props)