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//! Implement abstract syntax tree (AST) nodes for the python language.
//!
//! Roughly equivalent to [the python AST](https://docs.python.org/3/library/ast.html)
//! Many AST nodes have a location attribute, to determine the sourcecode
//! location of the node.
pub use crate::location::Location;
use num_bigint::BigInt;
#[allow(clippy::large_enum_variant)]
#[derive(Debug, PartialEq)]
pub enum Top {
Program(Program),
Statement(Vec<Statement>),
Expression(Expression),
}
#[derive(Debug, PartialEq)]
/// A full python program, it's a sequence of statements.
pub struct Program {
pub statements: Suite,
}
#[derive(Debug, PartialEq)]
pub struct ImportSymbol {
pub symbol: String,
pub alias: Option<String>,
}
#[derive(Debug, PartialEq)]
pub struct Located<T> {
pub location: Location,
pub node: T,
}
pub type Statement = Located<StatementType>;
pub type Suite = Vec<Statement>;
/// Abstract syntax tree nodes for python statements.
#[derive(Debug, PartialEq)]
pub enum StatementType {
/// A [`break`](https://docs.python.org/3/reference/simple_stmts.html#the-break-statement) statement.
Break,
/// A [`continue`](https://docs.python.org/3/reference/simple_stmts.html#the-continue-statement) statement.
Continue,
/// A [`return`](https://docs.python.org/3/reference/simple_stmts.html#the-return-statement) statement.
/// This is used to return from a function.
Return { value: Option<Expression> },
/// An [`import`](https://docs.python.org/3/reference/simple_stmts.html#the-import-statement) statement.
Import { names: Vec<ImportSymbol> },
/// An [`import` `from`](https://docs.python.org/3/reference/simple_stmts.html#the-import-statement) statement.
ImportFrom {
level: usize,
module: Option<String>,
names: Vec<ImportSymbol>,
},
/// A [`pass`](https://docs.python.org/3/reference/simple_stmts.html#pass) statement.
Pass,
/// An [`assert`](https://docs.python.org/3/reference/simple_stmts.html#the-assert-statement) statement.
Assert {
test: Expression,
msg: Option<Expression>,
},
/// A `del` statement, to delete some variables.
Delete { targets: Vec<Expression> },
/// Variable assignment. Note that we can assign to multiple targets.
Assign {
targets: Vec<Expression>,
value: Expression,
},
/// Augmented assignment.
AugAssign {
target: Box<Expression>,
op: Operator,
value: Box<Expression>,
},
/// A type annotated assignment.
AnnAssign {
target: Box<Expression>,
annotation: Box<Expression>,
value: Option<Expression>,
},
/// An expression used as a statement.
Expression { expression: Expression },
/// The [`global`](https://docs.python.org/3/reference/simple_stmts.html#the-global-statement) statement,
/// to declare names as global variables.
Global { names: Vec<String> },
/// A [`nonlocal`](https://docs.python.org/3/reference/simple_stmts.html#the-nonlocal-statement) statement,
/// to declare names a non-local variables.
Nonlocal { names: Vec<String> },
/// An [`if`](https://docs.python.org/3/reference/compound_stmts.html#the-if-statement) statement.
If {
test: Expression,
body: Suite,
orelse: Option<Suite>,
},
/// A [`while`](https://docs.python.org/3/reference/compound_stmts.html#the-while-statement) statement.
While {
test: Expression,
body: Suite,
orelse: Option<Suite>,
},
/// The [`with`](https://docs.python.org/3/reference/compound_stmts.html#the-with-statement) statement.
With {
is_async: bool,
items: Vec<WithItem>,
body: Suite,
},
/// A [`for`](https://docs.python.org/3/reference/compound_stmts.html#the-for-statement) statement.
/// Contains the body of the loop, and the `else` clause.
For {
is_async: bool,
target: Box<Expression>,
iter: Box<Expression>,
body: Suite,
orelse: Option<Suite>,
},
/// A `raise` statement.
Raise {
exception: Option<Expression>,
cause: Option<Expression>,
},
/// A [`try`](https://docs.python.org/3/reference/compound_stmts.html#the-try-statement) statement.
Try {
body: Suite,
handlers: Vec<ExceptHandler>,
orelse: Option<Suite>,
finalbody: Option<Suite>,
},
/// A [class definition](https://docs.python.org/3/reference/compound_stmts.html#class-definitions).
ClassDef {
name: String,
body: Suite,
bases: Vec<Expression>,
keywords: Vec<Keyword>,
decorator_list: Vec<Expression>,
},
/// A [function definition](https://docs.python.org/3/reference/compound_stmts.html#function-definitions).
/// Contains the name of the function, it's body
/// some decorators and formal parameters to the function.
FunctionDef {
is_async: bool,
name: String,
args: Box<Parameters>,
body: Suite,
decorator_list: Vec<Expression>,
returns: Option<Expression>,
},
}
#[derive(Debug, PartialEq)]
pub struct WithItem {
pub context_expr: Expression,
pub optional_vars: Option<Expression>,
}
/// An expression at a given location in the sourcecode.
pub type Expression = Located<ExpressionType>;
/// A certain type of expression.
#[derive(Debug, PartialEq)]
pub enum ExpressionType {
BoolOp {
op: BooleanOperator,
values: Vec<Expression>,
},
/// A binary operation on two operands.
Binop {
a: Box<Expression>,
op: Operator,
b: Box<Expression>,
},
/// Subscript operation.
Subscript {
a: Box<Expression>,
b: Box<Expression>,
},
/// An unary operation.
Unop {
op: UnaryOperator,
a: Box<Expression>,
},
/// An await expression.
Await {
value: Box<Expression>,
},
/// A yield expression.
Yield {
value: Option<Box<Expression>>,
},
// A yield from expression.
YieldFrom {
value: Box<Expression>,
},
/// A chained comparison. Note that in python you can use
/// `1 < a < 10` for example.
Compare {
vals: Vec<Expression>,
ops: Vec<Comparison>,
},
/// Attribute access in the form of `value.name`.
Attribute {
value: Box<Expression>,
name: String,
},
/// A call expression.
Call {
function: Box<Expression>,
args: Vec<Expression>,
keywords: Vec<Keyword>,
},
/// A numeric literal.
Number {
value: Number,
},
/// A `list` literal value.
List {
elements: Vec<Expression>,
},
/// A `tuple` literal value.
Tuple {
elements: Vec<Expression>,
},
/// A `dict` literal value.
/// For example: `{2: 'two', 3: 'three'}`
Dict {
elements: Vec<(Option<Expression>, Expression)>,
},
/// A `set` literal.
Set {
elements: Vec<Expression>,
},
Comprehension {
kind: Box<ComprehensionKind>,
generators: Vec<Comprehension>,
},
/// A starred expression.
Starred {
value: Box<Expression>,
},
/// A slice expression.
Slice {
elements: Vec<Expression>,
},
/// A string literal.
String {
value: StringGroup,
},
/// A bytes literal.
Bytes {
value: Vec<u8>,
},
/// An identifier, designating a certain variable or type.
Identifier {
name: String,
},
/// A `lambda` function expression.
Lambda {
args: Box<Parameters>,
body: Box<Expression>,
},
/// An if-expression.
IfExpression {
test: Box<Expression>,
body: Box<Expression>,
orelse: Box<Expression>,
},
// A named expression
NamedExpression {
left: Box<Expression>,
right: Box<Expression>,
},
/// The literal 'True'.
True,
/// The literal 'False'.
False,
// The literal `None`.
None,
/// The ellipsis literal `...`.
Ellipsis,
}
impl Expression {
/// Returns a short name for the node suitable for use in error messages.
pub fn name(&self) -> &'static str {
use self::ExpressionType::*;
use self::StringGroup::*;
match &self.node {
BoolOp { .. } | Binop { .. } | Unop { .. } => "operator",
Subscript { .. } => "subscript",
Await { .. } => "await expression",
Yield { .. } | YieldFrom { .. } => "yield expression",
Compare { .. } => "comparison",
Attribute { .. } => "attribute",
Call { .. } => "function call",
Number { .. }
| String {
value: Constant { .. },
}
| Bytes { .. } => "literal",
List { .. } => "list",
Tuple { .. } => "tuple",
Dict { .. } => "dict display",
Set { .. } => "set display",
Comprehension { kind, .. } => match **kind {
ComprehensionKind::List { .. } => "list comprehension",
ComprehensionKind::Dict { .. } => "dict comprehension",
ComprehensionKind::Set { .. } => "set comprehension",
ComprehensionKind::GeneratorExpression { .. } => "generator expression",
},
Starred { .. } => "starred",
Slice { .. } => "slice",
String {
value: Joined { .. },
}
| String {
value: FormattedValue { .. },
} => "f-string expression",
Identifier { .. } => "named expression",
Lambda { .. } => "lambda",
IfExpression { .. } => "conditional expression",
True | False | None => "keyword",
Ellipsis => "ellipsis",
NamedExpression { .. } => "named expression",
}
}
}
/// Formal parameters to a function.
///
/// In cpython this is called arguments, but we choose parameters to
/// distinguish between function parameters and actual call arguments.
#[derive(Debug, PartialEq, Default)]
pub struct Parameters {
pub posonlyargs_count: usize,
pub args: Vec<Parameter>,
pub kwonlyargs: Vec<Parameter>,
pub vararg: Varargs, // Optionally we handle optionally named '*args' or '*'
pub kwarg: Varargs,
pub defaults: Vec<Expression>,
pub kw_defaults: Vec<Option<Expression>>,
}
/// A single formal parameter to a function.
#[derive(Debug, PartialEq, Default)]
pub struct Parameter {
pub location: Location,
pub arg: String,
pub annotation: Option<Box<Expression>>,
}
#[allow(clippy::large_enum_variant)]
#[derive(Debug, PartialEq)]
pub enum ComprehensionKind {
GeneratorExpression { element: Expression },
List { element: Expression },
Set { element: Expression },
Dict { key: Expression, value: Expression },
}
/// A list/set/dict/generator compression.
#[derive(Debug, PartialEq)]
pub struct Comprehension {
pub location: Location,
pub target: Expression,
pub iter: Expression,
pub ifs: Vec<Expression>,
pub is_async: bool,
}
#[derive(Debug, PartialEq)]
pub struct ArgumentList {
pub args: Vec<Expression>,
pub keywords: Vec<Keyword>,
}
#[derive(Debug, PartialEq)]
pub struct Keyword {
pub name: Option<String>,
pub value: Expression,
}
#[derive(Debug, PartialEq)]
pub struct ExceptHandler {
pub location: Location,
pub typ: Option<Expression>,
pub name: Option<String>,
pub body: Suite,
}
/// An operator for a binary operation (an operation with two operands).
#[derive(Debug, PartialEq)]
pub enum Operator {
Add,
Sub,
Mult,
MatMult,
Div,
Mod,
Pow,
LShift,
RShift,
BitOr,
BitXor,
BitAnd,
FloorDiv,
}
/// A boolean operation.
#[derive(Debug, PartialEq)]
pub enum BooleanOperator {
And,
Or,
}
/// An unary operator. This is an operation with only a single operand.
#[derive(Debug, PartialEq)]
pub enum UnaryOperator {
Pos,
Neg,
Not,
Inv,
}
/// A comparison operation.
#[derive(Debug, PartialEq)]
pub enum Comparison {
Equal,
NotEqual,
Less,
LessOrEqual,
Greater,
GreaterOrEqual,
In,
NotIn,
Is,
IsNot,
}
/// A numeric literal.
#[derive(Debug, PartialEq)]
pub enum Number {
Integer { value: BigInt },
Float { value: f64 },
Complex { real: f64, imag: f64 },
}
/// Transforms a value prior to formatting it.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum ConversionFlag {
/// Converts by calling `str(<value>)`.
Str,
/// Converts by calling `ascii(<value>)`.
Ascii,
/// Converts by calling `repr(<value>)`.
Repr,
}
#[derive(Debug, PartialEq)]
pub enum StringGroup {
Constant {
value: String,
},
FormattedValue {
value: Box<Expression>,
conversion: Option<ConversionFlag>,
spec: Option<Box<StringGroup>>,
},
Joined {
values: Vec<StringGroup>,
},
}
#[derive(Debug, PartialEq)]
pub enum Varargs {
None,
Unnamed,
Named(Parameter),
}
impl Default for Varargs {
fn default() -> Varargs {
Varargs::None
}
}
impl From<Option<Option<Parameter>>> for Varargs {
fn from(opt: Option<Option<Parameter>>) -> Varargs {
match opt {
Some(inner_opt) => match inner_opt {
Some(param) => Varargs::Named(param),
None => Varargs::Unnamed,
},
None => Varargs::None,
}
}
}