Enum Expr 

pub enum Expr {
    Literal(CypherLiteral),
    Parameter(String),
    Variable(String),
    Wildcard,
    Property(Box<Expr>, String),
    List(Vec<Expr>),
    Map(Vec<(String, Expr)>),
    FunctionCall {
        name: String,
        args: Vec<Expr>,
        distinct: bool,
        window_spec: Option<WindowSpec>,
    },
    BinaryOp {
        left: Box<Expr>,
        op: BinaryOp,
        right: Box<Expr>,
    },
    UnaryOp {
        op: UnaryOp,
        expr: Box<Expr>,
    },
    Case {
        expr: Option<Box<Expr>>,
        when_then: Vec<(Expr, Expr)>,
        else_expr: Option<Box<Expr>>,
    },
    Exists {
        query: Box<Query>,
        from_pattern_predicate: bool,
    },
    CountSubquery(Box<Query>),
    CollectSubquery(Box<Query>),
    IsNull(Box<Expr>),
    IsNotNull(Box<Expr>),
    IsUnique(Box<Expr>),
    In {
        expr: Box<Expr>,
        list: Box<Expr>,
    },
    ArrayIndex {
        array: Box<Expr>,
        index: Box<Expr>,
    },
    ArraySlice {
        array: Box<Expr>,
        start: Option<Box<Expr>>,
        end: Option<Box<Expr>>,
    },
    Quantifier {
        quantifier: Quantifier,
        variable: String,
        list: Box<Expr>,
        predicate: Box<Expr>,
    },
    Reduce {
        accumulator: String,
        init: Box<Expr>,
        variable: String,
        list: Box<Expr>,
        expr: Box<Expr>,
    },
    ListComprehension {
        variable: String,
        list: Box<Expr>,
        where_clause: Option<Box<Expr>>,
        map_expr: Box<Expr>,
    },
    PatternComprehension {
        path_variable: Option<String>,
        pattern: Pattern,
        where_clause: Option<Box<Expr>>,
        map_expr: Box<Expr>,
    },
    ValidAt {
        entity: Box<Expr>,
        timestamp: Box<Expr>,
        start_prop: Option<String>,
        end_prop: Option<String>,
    },
    MapProjection {
        base: Box<Expr>,
        items: Vec<MapProjectionItem>,
    },
    LabelCheck {
        expr: Box<Expr>,
        labels: Vec<String>,
    },
}

Variants

Literal(CypherLiteral)

Parameter(String)

Variable(String)

Wildcard

Property(Box<Expr>, String)

List(Vec<Expr>)

Map(Vec<(String, Expr)>)

FunctionCall

Fields

name: String

args: Vec<Expr>

distinct: bool

window_spec: Option<WindowSpec>

BinaryOp

Fields

left: Box<Expr>

op: BinaryOp

right: Box<Expr>

UnaryOp

Fields

op: UnaryOp

expr: Box<Expr>

Case

Fields

expr: Option<Box<Expr>>

when_then: Vec<(Expr, Expr)>

else_expr: Option<Box<Expr>>

Exists

Fields

query: Box<Query>

from_pattern_predicate: bool

True when created from a bare pattern predicate (n)-->() in expression context.

CountSubquery(Box<Query>)

CollectSubquery(Box<Query>)

IsNull(Box<Expr>)

IsNotNull(Box<Expr>)

IsUnique(Box<Expr>)

In

Fields

expr: Box<Expr>

list: Box<Expr>

ArrayIndex

Fields

array: Box<Expr>

index: Box<Expr>

ArraySlice

Fields

array: Box<Expr>

start: Option<Box<Expr>>

end: Option<Box<Expr>>

Quantifier

Fields

quantifier: Quantifier

variable: String

list: Box<Expr>

predicate: Box<Expr>

Reduce

Fields

accumulator: String

init: Box<Expr>

variable: String

list: Box<Expr>

expr: Box<Expr>

ListComprehension

Fields

variable: String

list: Box<Expr>

where_clause: Option<Box<Expr>>

map_expr: Box<Expr>

PatternComprehension

Fields

path_variable: Option<String>

pattern: Pattern

where_clause: Option<Box<Expr>>

map_expr: Box<Expr>

ValidAt

Fields

entity: Box<Expr>

timestamp: Box<Expr>

start_prop: Option<String>

end_prop: Option<String>

MapProjection

Fields

base: Box<Expr>

items: Vec<MapProjectionItem>

LabelCheck

Label check expression: a:B or conjunctive a:A:B

Fields

expr: Box<Expr>

labels: Vec<String>

Implementations

impl Expr

pub const TRUE: Expr

Sentinel expression representing a literal true.

Useful in the planner for predicate reduction: when all conjuncts have been pushed down, the remaining predicate is replaced with this constant.

pub fn is_true_literal(&self) -> bool

Returns true if this expression is the literal boolean true.

pub fn extract_variable(&self) -> Option<String>

Extract a simple variable name if this expression is just a variable reference

pub fn substitute_variable(&self, old_var: &str, new_var: &str) -> Expr

Substitute all occurrences of a variable with a new variable name.

Structural variants (no binders, no special-case items) delegate to map_children, which is the canonical place where the full Expr variant set is enumerated. Only the variants with non-mechanical behavior — the matching Variable, variable-binders that introduce shadowing (Quantifier, Reduce, ListComprehension, PatternComprehension), and MapProjection whose Variable projection items must be rewritten — get explicit arms.

pub fn is_aggregate(&self) -> bool

Check if this expression contains an aggregate function

pub fn to_string_repr(&self) -> String

Generate a string representation of this expression for debugging/display

pub fn for_each_child(&self, f: &mut dyn FnMut(&Expr))

Call f on each direct child expression (non-recursive).

Does NOT descend into subqueries (Exists, CountSubquery, CollectSubquery) since those have separate variable scope.

pub fn map_children(self, f: &mut dyn FnMut(Expr) -> Expr) -> Expr

Map each direct child expression through f, producing a new Expr.

Same scoping rules as for_each_child: does not descend into subqueries.

Trait Implementations

impl Clone for Expr

fn clone(&self) -> Expr

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Expr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Expr

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Expr

fn eq(&self, other: &Expr) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Expr

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Expr