[lvgl] base implementation (#7116)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/components/lvgl/lvcode.py

@@ -0,0 +1,237 @@
+import abc
+import logging
+from typing import Union
+
+from esphome import codegen as cg
+from esphome.core import ID, Lambda
+from esphome.cpp_generator import (
+    AssignmentExpression,
+    CallExpression,
+    Expression,
+    LambdaExpression,
+    Literal,
+    MockObj,
+    RawExpression,
+    RawStatement,
+    SafeExpType,
+    Statement,
+    VariableDeclarationExpression,
+    statement,
+)
+
+from .helpers import get_line_marks
+
+_LOGGER = logging.getLogger(__name__)
+
+
+class CodeContext(abc.ABC):
+    """
+    A class providing a context for code generation. Generated code will be added to the
+    current context. A new context will stack on the current context, and restore it
+    when done. Used with the `with` statement.
+    """
+
+    code_context = None
+
+    @abc.abstractmethod
+    def add(self, expression: Union[Expression, Statement]):
+        pass
+
+    @staticmethod
+    def append(expression: Union[Expression, Statement]):
+        if CodeContext.code_context is not None:
+            CodeContext.code_context.add(expression)
+        return expression
+
+    def __init__(self):
+        self.previous: Union[CodeContext | None] = None
+
+    def __enter__(self):
+        self.previous = CodeContext.code_context
+        CodeContext.code_context = self
+
+    def __exit__(self, *args):
+        CodeContext.code_context = self.previous
+
+
+class MainContext(CodeContext):
+    """
+    Code generation into the main() function
+    """
+
+    def add(self, expression: Union[Expression, Statement]):
+        return cg.add(expression)
+
+
+class LvContext(CodeContext):
+    """
+    Code generation into the LVGL initialisation code (called in `setup()`)
+    """
+
+    lv_init_code: list["Statement"] = []
+
+    @staticmethod
+    def lv_add(expression: Union[Expression, Statement]):
+        if isinstance(expression, Expression):
+            expression = statement(expression)
+        if not isinstance(expression, Statement):
+            raise ValueError(
+                f"Add '{expression}' must be expression or statement, not {type(expression)}"
+            )
+        LvContext.lv_init_code.append(expression)
+        _LOGGER.debug("LV Adding: %s", expression)
+        return expression
+
+    @staticmethod
+    def get_code():
+        code = []
+        for exp in LvContext.lv_init_code:
+            text = str(statement(exp))
+            text = text.rstrip()
+            code.append(text)
+        return "\n".join(code) + "\n\n"
+
+    def add(self, expression: Union[Expression, Statement]):
+        return LvContext.lv_add(expression)
+
+    def set_style(self, prop):
+        return MockObj("lv_set_style_{prop}", "")
+
+
+class LambdaContext(CodeContext):
+    """
+    A context that will accumlate code for use in a lambda.
+    """
+
+    def __init__(
+        self,
+        parameters: list[tuple[SafeExpType, str]],
+        return_type: SafeExpType = None,
+    ):
+        super().__init__()
+        self.code_list: list[Statement] = []
+        self.parameters = parameters
+        self.return_type = return_type
+
+    def add(self, expression: Union[Expression, Statement]):
+        self.code_list.append(expression)
+        return expression
+
+    async def code(self) -> LambdaExpression:
+        code_text = []
+        for exp in self.code_list:
+            text = str(statement(exp))
+            text = text.rstrip()
+            code_text.append(text)
+        return await cg.process_lambda(
+            Lambda("\n".join(code_text) + "\n\n"),
+            self.parameters,
+            return_type=self.return_type,
+        )
+
+
+class LocalVariable(MockObj):
+    """
+    Create a local variable and enclose the code using it within a block.
+    """
+
+    def __init__(self, name, type, modifier=None, rhs=None):
+        base = ID(name, True, type)
+        super().__init__(base, "")
+        self.modifier = modifier
+        self.rhs = rhs
+
+    def __enter__(self):
+        CodeContext.append(RawStatement("{"))
+        CodeContext.append(
+            VariableDeclarationExpression(self.base.type, self.modifier, self.base.id)
+        )
+        if self.rhs is not None:
+            CodeContext.append(AssignmentExpression(None, "", self.base, self.rhs))
+        return self.base
+
+    def __exit__(self, *args):
+        CodeContext.append(RawStatement("}"))
+
+
+class MockLv:
+    """
+    A mock object that can be used to generate LVGL calls.
+    """
+
+    def __init__(self, base):
+        self.base = base
+
+    def __getattr__(self, attr: str) -> "MockLv":
+        return MockLv(f"{self.base}{attr}")
+
+    def append(self, expression):
+        CodeContext.append(expression)
+
+    def __call__(self, *args: SafeExpType) -> "MockObj":
+        call = CallExpression(self.base, *args)
+        result = MockObj(call, "")
+        self.append(result)
+        return result
+
+    def __str__(self):
+        return str(self.base)
+
+    def __repr__(self):
+        return f"MockLv<{str(self.base)}>"
+
+    def call(self, prop, *args):
+        call = CallExpression(RawExpression(f"{self.base}{prop}"), *args)
+        result = MockObj(call, "")
+        self.append(result)
+        return result
+
+    def cond_if(self, expression: Expression):
+        CodeContext.append(RawExpression(f"if({expression}) {{"))
+
+    def cond_else(self):
+        CodeContext.append(RawExpression("} else {"))
+
+    def cond_endif(self):
+        CodeContext.append(RawExpression("}"))
+
+
+class LvExpr(MockLv):
+    def __getattr__(self, attr: str) -> "MockLv":
+        return LvExpr(f"{self.base}{attr}")
+
+    def append(self, expression):
+        pass
+
+
+# Top level mock for generic lv_ calls to be recorded
+lv = MockLv("lv_")
+# Just generate an expression
+lv_expr = LvExpr("lv_")
+# Mock for lv_obj_ calls
+lv_obj = MockLv("lv_obj_")
+
+
+# equivalent to cg.add() for the lvgl init context
+def lv_add(expression: Union[Expression, Statement]):
+    return CodeContext.append(expression)
+
+
+def add_line_marks(where):
+    for mark in get_line_marks(where):
+        lv_add(cg.RawStatement(mark))
+
+
+def lv_assign(target, expression):
+    lv_add(RawExpression(f"{target} = {expression}"))
+
+
+class ConstantLiteral(Literal):
+    __slots__ = ("constant",)
+
+    def __init__(self, constant: str):
+        super().__init__()
+        self.constant = constant
+
+    def __str__(self):
+        return self.constant