runmat_runtime/builtins/array/sorting_sets/

unique.rs

//! MATLAB-compatible `unique` builtin with GPU-aware semantics for RunMat.
//!
//! The implementation mirrors MathWorks MATLAB behavioural details for sorted
//! and stable orderings, row-wise uniqueness, and index outputs. GPU tensors
//! are gathered to host memory today, but the builtin is registered as a sink
//! so future providers can add device-side kernels without impacting callers.

use std::cmp::Ordering;
use std::collections::HashMap;

use runmat_accelerate_api::{
    GpuTensorHandle, GpuTensorStorage, HostTensorOwned, UniqueOccurrence, UniqueOptions,
    UniqueOrder, UniqueResult,
};
use runmat_builtins::{CharArray, ComplexTensor, StringArray, Tensor, Value};
use runmat_macros::runtime_builtin;

use super::type_resolvers::set_values_output_type;
use crate::build_runtime_error;
use crate::builtins::common::arg_tokens::tokens_from_values;
use crate::builtins::common::gpu_helpers;
use crate::builtins::common::random_args::complex_tensor_into_value;
use crate::builtins::common::spec::{
    BroadcastSemantics, BuiltinFusionSpec, BuiltinGpuSpec, ConstantStrategy, GpuOpKind,
    ProviderHook, ReductionNaN, ResidencyPolicy, ScalarType, ShapeRequirements,
};
use crate::builtins::common::tensor;

#[runmat_macros::register_gpu_spec(builtin_path = "crate::builtins::array::sorting_sets::unique")]
pub const GPU_SPEC: BuiltinGpuSpec = BuiltinGpuSpec {
    name: "unique",
    op_kind: GpuOpKind::Custom("unique"),
    supported_precisions: &[ScalarType::F32, ScalarType::F64],
    broadcast: BroadcastSemantics::None,
    provider_hooks: &[ProviderHook::Custom("unique")],
    constant_strategy: ConstantStrategy::InlineLiteral,
    residency: ResidencyPolicy::GatherImmediately,
    nan_mode: ReductionNaN::Include,
    two_pass_threshold: None,
    workgroup_size: None,
    accepts_nan_mode: true,
    notes: "Providers may implement the `unique` hook; default providers download tensors and reuse the CPU implementation.",
};

#[runmat_macros::register_fusion_spec(
    builtin_path = "crate::builtins::array::sorting_sets::unique"
)]
pub const FUSION_SPEC: BuiltinFusionSpec = BuiltinFusionSpec {
    name: "unique",
    shape: ShapeRequirements::Any,
    constant_strategy: ConstantStrategy::InlineLiteral,
    elementwise: None,
    reduction: None,
    emits_nan: true,
    notes: "`unique` terminates fusion chains and materialises results on the host; upstream tensors are gathered when necessary.",
};

fn unique_error(message: impl Into<String>) -> crate::RuntimeError {
    build_runtime_error(message).with_builtin("unique").build()
}

#[runtime_builtin(
    name = "unique",
    category = "array/sorting_sets",
    summary = "Return the unique elements or rows of arrays with optional index outputs.",
    keywords = "unique,set,distinct,stable,rows,indices,gpu",
    accel = "array_construct",
    sink = true,
    type_resolver(set_values_output_type),
    builtin_path = "crate::builtins::array::sorting_sets::unique"
)]
async fn unique_builtin(value: Value, rest: Vec<Value>) -> crate::BuiltinResult<Value> {
    let eval = evaluate(value, &rest).await?;
    if let Some(out_count) = crate::output_count::current_output_count() {
        if out_count == 0 {
            return Ok(Value::OutputList(Vec::new()));
        }
        if out_count == 1 {
            return Ok(Value::OutputList(vec![eval.into_values_value()]));
        }
        if out_count == 2 {
            let (values, ia) = eval.into_pair();
            return Ok(Value::OutputList(vec![values, ia]));
        }
        let (values, ia, ic) = eval.into_triple();
        return Ok(crate::output_count::output_list_with_padding(
            out_count,
            vec![values, ia, ic],
        ));
    }
    Ok(eval.into_values_value())
}

/// Evaluate `unique` once and expose all outputs to the caller.
pub async fn evaluate(value: Value, rest: &[Value]) -> crate::BuiltinResult<UniqueEvaluation> {
    let opts = parse_options(rest)?;
    match value {
        Value::GpuTensor(handle) => unique_gpu(handle, &opts).await,
        other => unique_host(other, &opts),
    }
}

fn parse_options(rest: &[Value]) -> crate::BuiltinResult<UniqueOptions> {
    let mut opts = UniqueOptions {
        rows: false,
        order: UniqueOrder::Sorted,
        occurrence: UniqueOccurrence::First,
    };
    let mut seen_order: Option<UniqueOrder> = None;
    let mut seen_occurrence: Option<UniqueOccurrence> = None;

    let tokens = tokens_from_values(rest);
    for (arg, token) in rest.iter().zip(tokens.iter()) {
        let text = match token {
            crate::builtins::common::arg_tokens::ArgToken::String(text) => text.as_str(),
            _ => {
                let text = tensor::value_to_string(arg)
                    .ok_or_else(|| unique_error("unique: expected string option arguments"))?;
                let lowered = text.trim().to_ascii_lowercase();
                parse_unique_option(&mut opts, &mut seen_order, &mut seen_occurrence, &lowered)?;
                continue;
            }
        };
        parse_unique_option(&mut opts, &mut seen_order, &mut seen_occurrence, text)?;
    }

    Ok(opts)
}

fn parse_unique_option(
    opts: &mut UniqueOptions,
    seen_order: &mut Option<UniqueOrder>,
    seen_occurrence: &mut Option<UniqueOccurrence>,
    lowered: &str,
) -> crate::BuiltinResult<()> {
    match lowered {
        "sorted" => {
            if let Some(prev) = seen_order {
                if *prev != UniqueOrder::Sorted {
                    return Err(unique_error(
                        "unique: cannot combine 'sorted' with 'stable'",
                    ));
                }
            }
            *seen_order = Some(UniqueOrder::Sorted);
            opts.order = UniqueOrder::Sorted;
        }
        "stable" => {
            if let Some(prev) = seen_order {
                if *prev != UniqueOrder::Stable {
                    return Err(unique_error(
                        "unique: cannot combine 'sorted' with 'stable'",
                    ));
                }
            }
            *seen_order = Some(UniqueOrder::Stable);
            opts.order = UniqueOrder::Stable;
        }
        "rows" => {
            opts.rows = true;
        }
        "first" => {
            if let Some(prev) = seen_occurrence {
                if *prev != UniqueOccurrence::First {
                    return Err(unique_error("unique: cannot combine 'first' with 'last'"));
                }
            }
            *seen_occurrence = Some(UniqueOccurrence::First);
            opts.occurrence = UniqueOccurrence::First;
        }
        "last" => {
            if let Some(prev) = seen_occurrence {
                if *prev != UniqueOccurrence::Last {
                    return Err(unique_error("unique: cannot combine 'first' with 'last'"));
                }
            }
            *seen_occurrence = Some(UniqueOccurrence::Last);
            opts.occurrence = UniqueOccurrence::Last;
        }
        "legacy" | "r2012a" => {
            return Err(unique_error(
                "unique: the 'legacy' behaviour is not supported",
            ));
        }
        other => {
            return Err(unique_error(format!(
                "unique: unrecognised option '{other}'"
            )));
        }
    }
    Ok(())
}

async fn unique_gpu(
    handle: GpuTensorHandle,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if let Some(provider) = runmat_accelerate_api::provider() {
        if let Ok(result) = provider.unique(&handle, opts).await {
            return UniqueEvaluation::from_unique_result(result);
        }
    }
    let tensor = gpu_helpers::gather_tensor_async(&handle).await?;
    unique_numeric_from_tensor(tensor, opts)
}

fn unique_host(value: Value, opts: &UniqueOptions) -> crate::BuiltinResult<UniqueEvaluation> {
    match value {
        Value::Tensor(tensor) => unique_numeric_from_tensor(tensor, opts),
        Value::Num(n) => {
            let tensor = Tensor::new(vec![n], vec![1, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
            unique_numeric_from_tensor(tensor, opts)
        }
        Value::Int(i) => {
            let tensor = Tensor::new(vec![i.to_f64()], vec![1, 1])
                .map_err(|e| unique_error(format!("unique: {e}")))?;
            unique_numeric_from_tensor(tensor, opts)
        }
        Value::Bool(b) => {
            let tensor = Tensor::new(vec![if b { 1.0 } else { 0.0 }], vec![1, 1])
                .map_err(|e| unique_error(format!("unique: {e}")))?;
            unique_numeric_from_tensor(tensor, opts)
        }
        Value::LogicalArray(logical) => {
            let tensor = tensor::logical_to_tensor(&logical)
                .map_err(|e| unique_error(e))?;
            unique_numeric_from_tensor(tensor, opts)
        }
        Value::ComplexTensor(tensor) => unique_complex_from_tensor(tensor, opts),
        Value::Complex(re, im) => {
            let tensor = ComplexTensor::new(vec![(re, im)], vec![1, 1])
                .map_err(|e| unique_error(format!("unique: {e}")))?;
            unique_complex_from_tensor(tensor, opts)
        }
        Value::CharArray(array) => unique_char_array(array, opts),
        Value::StringArray(array) => unique_string_array(array, opts),
        Value::String(s) => {
            let array = StringArray::new(vec![s], vec![1, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
            unique_string_array(array, opts)
        }
        other => Err(unique_error(format!(
            "unique: unsupported input type {:?}; expected numeric, logical, char, string, or complex values",
            other
        ))
        .into()),
    }
}

pub fn unique_numeric_from_tensor(
    tensor: Tensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if opts.rows {
        unique_numeric_rows(tensor, opts)
    } else {
        unique_numeric_elements(tensor, opts)
    }
}

fn unique_numeric_elements(
    tensor: Tensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    let len = tensor.data.len();
    if len == 0 {
        let values = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(
            tensor::tensor_into_value(values),
            ia,
            ic,
        ));
    }

    let mut entries = Vec::<NumericElementEntry>::new();
    let mut map: HashMap<u64, usize> = HashMap::new();
    let mut element_entry_index = Vec::with_capacity(len);

    for (idx, &value) in tensor.data.iter().enumerate() {
        let key = canonicalize_f64(value);
        match map.get(&key) {
            Some(&entry_idx) => {
                entries[entry_idx].last = idx;
                element_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(NumericElementEntry {
                    value,
                    first: idx,
                    last: idx,
                });
                map.insert(key, entry_idx);
                element_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_f64(entries[a].value, entries[b].value));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let mut values = Vec::with_capacity(order.len());
    let mut ia = Vec::with_capacity(order.len());
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        values.push(entry.value);
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(len);
    for entry_idx in element_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_tensor = Tensor::new(values, vec![order.len(), 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor =
        Tensor::new(ia, vec![order.len(), 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![len, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        tensor::tensor_into_value(value_tensor),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_numeric_rows(
    tensor: Tensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if tensor.shape.len() != 2 {
        return Err(unique_error(
            "unique: 'rows' option requires a 2-D matrix input",
        ));
    }
    let rows = tensor.shape[0];
    let cols = tensor.shape[1];

    if rows == 0 || cols == 0 {
        let values = Tensor::new(Vec::new(), vec![0, cols])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![rows, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(
            tensor::tensor_into_value(values),
            ia,
            ic,
        ));
    }

    let mut entries = Vec::<NumericRowEntry>::new();
    let mut map: HashMap<NumericRowKey, usize> = HashMap::new();
    let mut row_entry_index = Vec::with_capacity(rows);

    for r in 0..rows {
        let mut row_values = Vec::with_capacity(cols);
        for c in 0..cols {
            let idx = r + c * rows;
            row_values.push(tensor.data[idx]);
        }
        let key = NumericRowKey::from_slice(&row_values);
        match map.get(&key) {
            Some(&entry_idx) => {
                entries[entry_idx].last = r;
                row_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(NumericRowEntry {
                    row_data: row_values.clone(),
                    first: r,
                    last: r,
                });
                map.insert(key, entry_idx);
                row_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_numeric_rows(&entries[a].row_data, &entries[b].row_data));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let unique_rows_count = order.len();
    let mut values = vec![0.0f64; unique_rows_count * cols];
    for (row_pos, &entry_idx) in order.iter().enumerate() {
        let row = &entries[entry_idx].row_data;
        for (col, value) in row.iter().enumerate().take(cols) {
            let dest = row_pos + col * unique_rows_count;
            values[dest] = *value;
        }
    }

    let mut ia = Vec::with_capacity(unique_rows_count);
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(rows);
    for entry_idx in row_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_tensor = Tensor::new(values, vec![unique_rows_count, cols])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor = Tensor::new(ia, vec![unique_rows_count, 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![rows, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        tensor::tensor_into_value(value_tensor),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_complex_from_tensor(
    tensor: ComplexTensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if opts.rows {
        unique_complex_rows(tensor, opts)
    } else {
        unique_complex_elements(tensor, opts)
    }
}

fn unique_complex_elements(
    tensor: ComplexTensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    let len = tensor.data.len();
    if len == 0 {
        let values = ComplexTensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(
            complex_tensor_into_value(values),
            ia,
            ic,
        ));
    }

    let mut entries = Vec::<ComplexElementEntry>::new();
    let mut map: HashMap<ComplexKey, usize> = HashMap::new();
    let mut element_entry_index = Vec::with_capacity(len);

    for (idx, &value) in tensor.data.iter().enumerate() {
        let key = ComplexKey::new(value);
        match map.get(&key) {
            Some(&entry_idx) => {
                entries[entry_idx].last = idx;
                element_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(ComplexElementEntry {
                    value,
                    first: idx,
                    last: idx,
                });
                map.insert(key, entry_idx);
                element_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_complex(entries[a].value, entries[b].value));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let mut values = Vec::with_capacity(order.len());
    let mut ia = Vec::with_capacity(order.len());
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        values.push(entry.value);
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(len);
    for entry_idx in element_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_tensor = ComplexTensor::new(values, vec![order.len(), 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor =
        Tensor::new(ia, vec![order.len(), 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![len, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        complex_tensor_into_value(value_tensor),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_complex_rows(
    tensor: ComplexTensor,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if tensor.shape.len() != 2 {
        return Err(unique_error(
            "unique: 'rows' option requires a 2-D matrix input",
        ));
    }
    let rows = tensor.shape[0];
    let cols = tensor.shape[1];

    if rows == 0 || cols == 0 {
        let values = ComplexTensor::new(Vec::new(), vec![rows, cols])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![rows, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(
            complex_tensor_into_value(values),
            ia,
            ic,
        ));
    }

    let mut entries = Vec::<ComplexRowEntry>::new();
    let mut map: HashMap<Vec<ComplexKey>, usize> = HashMap::new();
    let mut row_entry_index = Vec::with_capacity(rows);

    for r in 0..rows {
        let mut row_values = Vec::with_capacity(cols);
        let mut key_row = Vec::with_capacity(cols);
        for c in 0..cols {
            let idx = r + c * rows;
            let value = tensor.data[idx];
            row_values.push(value);
            key_row.push(ComplexKey::new(value));
        }
        match map.get(&key_row) {
            Some(&entry_idx) => {
                entries[entry_idx].last = r;
                row_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(ComplexRowEntry {
                    row_data: row_values.clone(),
                    first: r,
                    last: r,
                });
                map.insert(key_row, entry_idx);
                row_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_complex_rows(&entries[a].row_data, &entries[b].row_data));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let unique_rows_count = order.len();
    let mut values = vec![(0.0, 0.0); unique_rows_count * cols];
    for (row_pos, &entry_idx) in order.iter().enumerate() {
        let row = &entries[entry_idx].row_data;
        for (col, value) in row.iter().enumerate().take(cols) {
            let dest = row_pos + col * unique_rows_count;
            values[dest] = *value;
        }
    }

    let mut ia = Vec::with_capacity(unique_rows_count);
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(rows);
    for entry_idx in row_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_tensor = ComplexTensor::new(values, vec![unique_rows_count, cols])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor = Tensor::new(ia, vec![unique_rows_count, 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![rows, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        complex_tensor_into_value(value_tensor),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_char_array(
    array: CharArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if opts.rows {
        unique_char_rows(array, opts)
    } else {
        unique_char_elements(array, opts)
    }
}

fn unique_char_elements(
    array: CharArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    let rows = array.rows;
    let cols = array.cols;
    let total = rows * cols;
    if total == 0 {
        let values =
            CharArray::new(Vec::new(), 0, 0).map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(Value::CharArray(values), ia, ic));
    }

    let mut entries = Vec::<CharElementEntry>::new();
    let mut map: HashMap<u32, usize> = HashMap::new();
    let mut element_entry_index = Vec::with_capacity(total);

    for col in 0..cols {
        for row in 0..rows {
            let linear_idx = row + col * rows;
            let data_idx = row * cols + col;
            let ch = array.data[data_idx];
            let key = ch as u32;
            match map.get(&key) {
                Some(&entry_idx) => {
                    entries[entry_idx].last = linear_idx;
                    element_entry_index.push(entry_idx);
                }
                None => {
                    let entry_idx = entries.len();
                    entries.push(CharElementEntry {
                        ch,
                        first: linear_idx,
                        last: linear_idx,
                    });
                    map.insert(key, entry_idx);
                    element_entry_index.push(entry_idx);
                }
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| entries[a].ch.cmp(&entries[b].ch));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let mut values = Vec::with_capacity(order.len());
    let mut ia = Vec::with_capacity(order.len());
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        values.push(entry.ch);
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(total);
    for entry_idx in element_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_array =
        CharArray::new(values, order.len(), 1).map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor =
        Tensor::new(ia, vec![order.len(), 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![total, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        Value::CharArray(value_array),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_char_rows(
    array: CharArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    let rows = array.rows;
    let cols = array.cols;
    if rows == 0 {
        let values = CharArray::new(Vec::new(), 0, cols)
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(Value::CharArray(values), ia, ic));
    }

    let mut entries = Vec::<CharRowEntry>::new();
    let mut map: HashMap<RowCharKey, usize> = HashMap::new();
    let mut row_entry_index = Vec::with_capacity(rows);

    for r in 0..rows {
        let start = r * cols;
        let end = start + cols;
        let slice = &array.data[start..end];
        let key = RowCharKey::from_slice(slice);
        match map.get(&key) {
            Some(&entry_idx) => {
                entries[entry_idx].last = r;
                row_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(CharRowEntry {
                    row_data: slice.to_vec(),
                    first: r,
                    last: r,
                });
                map.insert(key, entry_idx);
                row_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_char_rows(&entries[a].row_data, &entries[b].row_data));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let unique_rows_count = order.len();
    let mut values = vec!['\0'; unique_rows_count * cols];
    for (row_pos, &entry_idx) in order.iter().enumerate() {
        let row = &entries[entry_idx].row_data;
        for col in 0..cols {
            let dest = row_pos * cols + col;
            if col < row.len() {
                values[dest] = row[col];
            }
        }
    }

    let mut ia = Vec::with_capacity(unique_rows_count);
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(rows);
    for entry_idx in row_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_array = CharArray::new(values, unique_rows_count, cols)
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor = Tensor::new(ia, vec![unique_rows_count, 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![rows, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        Value::CharArray(value_array),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_string_array(
    array: StringArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if opts.rows {
        unique_string_rows(array, opts)
    } else {
        unique_string_elements(array, opts)
    }
}

fn unique_string_elements(
    array: StringArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    let len = array.data.len();
    if len == 0 {
        let values = StringArray::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(Value::StringArray(values), ia, ic));
    }

    let mut entries = Vec::<StringElementEntry>::new();
    let mut map: HashMap<String, usize> = HashMap::new();
    let mut element_entry_index = Vec::with_capacity(len);

    for (idx, value) in array.data.iter().enumerate() {
        match map.get(value) {
            Some(&entry_idx) => {
                entries[entry_idx].last = idx;
                element_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(StringElementEntry {
                    value: value.clone(),
                    first: idx,
                    last: idx,
                });
                map.insert(value.clone(), entry_idx);
                element_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| entries[a].value.cmp(&entries[b].value));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let mut values = Vec::with_capacity(order.len());
    let mut ia = Vec::with_capacity(order.len());
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        values.push(entry.value.clone());
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(len);
    for entry_idx in element_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_array = StringArray::new(values, vec![order.len(), 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor =
        Tensor::new(ia, vec![order.len(), 1]).map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![len, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        Value::StringArray(value_array),
        ia_tensor,
        ic_tensor,
    ))
}

fn unique_string_rows(
    array: StringArray,
    opts: &UniqueOptions,
) -> crate::BuiltinResult<UniqueEvaluation> {
    if array.shape.len() != 2 {
        return Err(unique_error(
            "unique: 'rows' option requires a 2-D matrix input",
        ));
    }
    let rows = array.shape[0];
    let cols = array.shape[1];

    if rows == 0 {
        let values = StringArray::new(Vec::new(), vec![0, cols])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic = Tensor::new(Vec::new(), vec![0, 1])
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        return Ok(UniqueEvaluation::new(Value::StringArray(values), ia, ic));
    }

    let mut entries = Vec::<StringRowEntry>::new();
    let mut map: HashMap<RowStringKey, usize> = HashMap::new();
    let mut row_entry_index = Vec::with_capacity(rows);

    for r in 0..rows {
        let mut row_values = Vec::with_capacity(cols);
        for c in 0..cols {
            let idx = r + c * rows;
            row_values.push(array.data[idx].clone());
        }
        let key = RowStringKey(row_values.clone());
        match map.get(&key) {
            Some(&entry_idx) => {
                entries[entry_idx].last = r;
                row_entry_index.push(entry_idx);
            }
            None => {
                let entry_idx = entries.len();
                entries.push(StringRowEntry {
                    row_data: row_values.clone(),
                    first: r,
                    last: r,
                });
                map.insert(key, entry_idx);
                row_entry_index.push(entry_idx);
            }
        }
    }

    let mut order: Vec<usize> = (0..entries.len()).collect();
    if opts.order == UniqueOrder::Sorted {
        order.sort_by(|&a, &b| compare_string_rows(&entries[a].row_data, &entries[b].row_data));
    }

    let mut entry_to_position = vec![0usize; entries.len()];
    for (pos, &entry_idx) in order.iter().enumerate() {
        entry_to_position[entry_idx] = pos;
    }

    let unique_rows_count = order.len();
    let mut values = vec![String::new(); unique_rows_count * cols];
    for (row_pos, &entry_idx) in order.iter().enumerate() {
        let row = &entries[entry_idx].row_data;
        for (col, value) in row.iter().enumerate().take(cols) {
            let dest = row_pos + col * unique_rows_count;
            values[dest] = value.clone();
        }
    }

    let mut ia = Vec::with_capacity(unique_rows_count);
    for &entry_idx in &order {
        let entry = &entries[entry_idx];
        let occurrence = match opts.occurrence {
            UniqueOccurrence::First => entry.first,
            UniqueOccurrence::Last => entry.last,
        };
        ia.push((occurrence + 1) as f64);
    }

    let mut ic = Vec::with_capacity(rows);
    for entry_idx in row_entry_index {
        let pos = entry_to_position[entry_idx];
        ic.push((pos + 1) as f64);
    }

    let value_array = StringArray::new(values, vec![unique_rows_count, cols])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ia_tensor = Tensor::new(ia, vec![unique_rows_count, 1])
        .map_err(|e| unique_error(format!("unique: {e}")))?;
    let ic_tensor =
        Tensor::new(ic, vec![rows, 1]).map_err(|e| unique_error(format!("unique: {e}")))?;

    Ok(UniqueEvaluation::new(
        Value::StringArray(value_array),
        ia_tensor,
        ic_tensor,
    ))
}

#[derive(Debug)]
struct NumericElementEntry {
    value: f64,
    first: usize,
    last: usize,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct NumericRowKey(Vec<u64>);

impl NumericRowKey {
    fn from_slice(values: &[f64]) -> Self {
        NumericRowKey(values.iter().map(|&v| canonicalize_f64(v)).collect())
    }
}

#[derive(Debug, Clone)]
struct NumericRowEntry {
    row_data: Vec<f64>,
    first: usize,
    last: usize,
}

#[derive(Debug)]
struct ComplexElementEntry {
    value: (f64, f64),
    first: usize,
    last: usize,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
struct ComplexKey {
    re: u64,
    im: u64,
}

impl ComplexKey {
    fn new(value: (f64, f64)) -> Self {
        Self {
            re: canonicalize_f64(value.0),
            im: canonicalize_f64(value.1),
        }
    }
}

#[derive(Debug, Clone)]
struct ComplexRowEntry {
    row_data: Vec<(f64, f64)>,
    first: usize,
    last: usize,
}

#[derive(Debug)]
struct CharElementEntry {
    ch: char,
    first: usize,
    last: usize,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct RowCharKey(Vec<u32>);

impl RowCharKey {
    fn from_slice(values: &[char]) -> Self {
        RowCharKey(values.iter().map(|&ch| ch as u32).collect())
    }
}

#[derive(Debug, Clone)]
struct CharRowEntry {
    row_data: Vec<char>,
    first: usize,
    last: usize,
}

#[derive(Debug, Clone)]
struct StringElementEntry {
    value: String,
    first: usize,
    last: usize,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct RowStringKey(Vec<String>);

#[derive(Debug, Clone)]
struct StringRowEntry {
    row_data: Vec<String>,
    first: usize,
    last: usize,
}

fn canonicalize_f64(value: f64) -> u64 {
    if value.is_nan() {
        0x7ff8_0000_0000_0000u64
    } else if value == 0.0 {
        0u64
    } else {
        value.to_bits()
    }
}

fn compare_f64(a: f64, b: f64) -> Ordering {
    if a.is_nan() {
        if b.is_nan() {
            Ordering::Equal
        } else {
            Ordering::Greater
        }
    } else if b.is_nan() {
        Ordering::Less
    } else {
        a.partial_cmp(&b).unwrap_or(Ordering::Equal)
    }
}

fn compare_numeric_rows(a: &[f64], b: &[f64]) -> Ordering {
    for (lhs, rhs) in a.iter().zip(b.iter()) {
        let ord = compare_f64(*lhs, *rhs);
        if ord != Ordering::Equal {
            return ord;
        }
    }
    Ordering::Equal
}

fn complex_is_nan(value: (f64, f64)) -> bool {
    value.0.is_nan() || value.1.is_nan()
}

fn compare_complex(a: (f64, f64), b: (f64, f64)) -> Ordering {
    match (complex_is_nan(a), complex_is_nan(b)) {
        (true, true) => Ordering::Equal,
        (true, false) => Ordering::Greater,
        (false, true) => Ordering::Less,
        (false, false) => {
            let mag_a = a.0.hypot(a.1);
            let mag_b = b.0.hypot(b.1);
            let mag_cmp = compare_f64(mag_a, mag_b);
            if mag_cmp != Ordering::Equal {
                return mag_cmp;
            }
            let re_cmp = compare_f64(a.0, b.0);
            if re_cmp != Ordering::Equal {
                return re_cmp;
            }
            compare_f64(a.1, b.1)
        }
    }
}

fn compare_complex_rows(a: &[(f64, f64)], b: &[(f64, f64)]) -> Ordering {
    for (lhs, rhs) in a.iter().zip(b.iter()) {
        let ord = compare_complex(*lhs, *rhs);
        if ord != Ordering::Equal {
            return ord;
        }
    }
    Ordering::Equal
}

fn compare_char_rows(a: &[char], b: &[char]) -> Ordering {
    for (lhs, rhs) in a.iter().zip(b.iter()) {
        let ord = lhs.cmp(rhs);
        if ord != Ordering::Equal {
            return ord;
        }
    }
    Ordering::Equal
}

fn compare_string_rows(a: &[String], b: &[String]) -> Ordering {
    for (lhs, rhs) in a.iter().zip(b.iter()) {
        let ord = lhs.cmp(rhs);
        if ord != Ordering::Equal {
            return ord;
        }
    }
    Ordering::Equal
}

#[derive(Debug)]
pub struct UniqueEvaluation {
    values: Value,
    ia: Tensor,
    ic: Tensor,
}

impl UniqueEvaluation {
    fn new(values: Value, ia: Tensor, ic: Tensor) -> Self {
        Self { values, ia, ic }
    }

    pub fn into_values_value(self) -> Value {
        self.values
    }

    pub fn into_pair(self) -> (Value, Value) {
        let ia = tensor::tensor_into_value(self.ia);
        (self.values, ia)
    }

    pub fn into_triple(self) -> (Value, Value, Value) {
        let ia = tensor::tensor_into_value(self.ia);
        let ic = tensor::tensor_into_value(self.ic);
        (self.values, ia, ic)
    }

    pub fn from_unique_result(result: UniqueResult) -> crate::BuiltinResult<Self> {
        let UniqueResult { values, ia, ic } = result;
        let values_tensor = Tensor::new(values.data, values.shape)
            .map_err(|e| unique_error(format!("unique: {e}")))?;
        let ia_tensor =
            Tensor::new(ia.data, ia.shape).map_err(|e| unique_error(format!("unique: {e}")))?;
        let ic_tensor =
            Tensor::new(ic.data, ic.shape).map_err(|e| unique_error(format!("unique: {e}")))?;
        Ok(UniqueEvaluation::new(
            tensor::tensor_into_value(values_tensor),
            ia_tensor,
            ic_tensor,
        ))
    }

    pub fn into_numeric_unique_result(self) -> crate::BuiltinResult<UniqueResult> {
        let UniqueEvaluation { values, ia, ic } = self;
        let values_tensor =
            tensor::value_into_tensor_for("unique", values).map_err(|e| unique_error(e))?;
        Ok(UniqueResult {
            values: HostTensorOwned {
                data: values_tensor.data,
                shape: values_tensor.shape,
                storage: GpuTensorStorage::Real,
            },
            ia: HostTensorOwned {
                data: ia.data,
                shape: ia.shape,
                storage: GpuTensorStorage::Real,
            },
            ic: HostTensorOwned {
                data: ic.data,
                shape: ic.shape,
                storage: GpuTensorStorage::Real,
            },
        })
    }

    pub fn ia_value(&self) -> Value {
        tensor::tensor_into_value(self.ia.clone())
    }

    pub fn ic_value(&self) -> Value {
        tensor::tensor_into_value(self.ic.clone())
    }
}

#[cfg(test)]
pub(crate) mod tests {
    use super::*;
    use crate::builtins::common::test_support;
    use runmat_builtins::{
        CharArray, IntValue, LogicalArray, ResolveContext, StringArray, Tensor, Type, Value,
    };

    fn error_message(err: crate::RuntimeError) -> String {
        err.message().to_string()
    }

    fn evaluate_sync(value: Value, rest: &[Value]) -> crate::BuiltinResult<UniqueEvaluation> {
        futures::executor::block_on(evaluate(value, rest))
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_sorted_default() {
        let tensor = Tensor::new(vec![3.0, 1.0, 3.0, 2.0], vec![4, 1]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert_eq!(t.data, vec![1.0, 2.0, 3.0]);
                assert_eq!(t.shape, vec![3, 1]);
            }
            Value::Num(_) => panic!("expected tensor result"),
            other => panic!("unexpected result {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![2.0, 4.0, 1.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![3.0, 1.0, 3.0, 2.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[test]
    fn unique_type_resolver_numeric() {
        assert_eq!(
            set_values_output_type(&[Type::tensor()], &ResolveContext::new(Vec::new())),
            Type::tensor()
        );
    }

    #[test]
    fn unique_type_resolver_string_array() {
        assert_eq!(
            set_values_output_type(
                &[Type::cell_of(Type::String)],
                &ResolveContext::new(Vec::new()),
            ),
            Type::cell_of(Type::String)
        );
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_sorted_handles_nan() {
        let tensor = Tensor::new(vec![f64::NAN, 2.0, f64::NAN, 1.0], vec![4, 1]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[]).expect("unique");
        let (values, ..) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert_eq!(t.data.len(), 3);
                assert_eq!(t.data[0], 1.0);
                assert_eq!(t.data[1], 2.0);
                assert!(t.data[2].is_nan());
            }
            other => panic!("unexpected values {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_stable_with_nan() {
        let tensor = Tensor::new(vec![f64::NAN, 2.0, f64::NAN, 1.0], vec![4, 1]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[Value::from("stable")]).expect("unique");
        let (values, ..) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert!(t.data[0].is_nan());
                assert_eq!(t.data[1], 2.0);
                assert_eq!(t.data[2], 1.0);
            }
            other => panic!("unexpected values {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_stable_preserves_order() {
        let tensor = Tensor::new(vec![4.0, 2.0, 4.0, 1.0, 2.0], vec![5, 1]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[Value::from("stable")]).expect("unique");
        let (values, ia) = eval.into_pair();
        match values {
            Value::Tensor(t) => assert_eq!(t.data, vec![4.0, 2.0, 1.0]),
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 2.0, 4.0]),
            other => panic!("unexpected IA {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_last_occurrence() {
        let tensor = Tensor::new(vec![9.0, 8.0, 9.0, 7.0, 8.0], vec![5, 1]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[Value::from("last")]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::Tensor(t) => assert_eq!(t.data, vec![7.0, 8.0, 9.0]),
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![4.0, 5.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![3.0, 2.0, 3.0, 1.0, 2.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_rows_sorted_default() {
        let tensor = Tensor::new(vec![1.0, 1.0, 2.0, 1.0, 3.0, 3.0, 4.0, 2.0], vec![4, 2]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[Value::from("rows")]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert_eq!(t.shape, vec![3, 2]);
                assert_eq!(t.data, vec![1.0, 1.0, 2.0, 2.0, 3.0, 4.0]);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![4.0, 1.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![2.0, 2.0, 3.0, 1.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_rows_stable_last() {
        let tensor = Tensor::new(vec![1.0, 1.0, 2.0, 1.0, 1.0, 2.0], vec![3, 2]).unwrap();
        let eval = evaluate_sync(
            Value::Tensor(tensor),
            &[
                Value::from("rows"),
                Value::from("stable"),
                Value::from("last"),
            ],
        )
        .expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert_eq!(t.shape, vec![2, 2]);
                assert_eq!(t.data, vec![1.0, 2.0, 1.0, 2.0]);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![2.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 1.0, 2.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_char_elements_sorted() {
        let chars = CharArray::new(vec!['m', 'z', 'm', 'a'], 2, 2).unwrap();
        let eval = evaluate_sync(Value::CharArray(chars), &[]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::CharArray(arr) => {
                assert_eq!(arr.rows, 3);
                assert_eq!(arr.cols, 1);
                assert_eq!(arr.data, vec!['a', 'm', 'z']);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![4.0, 1.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![2.0, 2.0, 3.0, 1.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_char_rows_last() {
        let chars = CharArray::new(vec!['a', 'b', 'a', 'b', 'a', 'c'], 3, 2).unwrap();
        let eval = evaluate_sync(
            Value::CharArray(chars),
            &[Value::from("rows"), Value::from("last")],
        )
        .expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::CharArray(arr) => {
                assert_eq!(arr.rows, 2);
                assert_eq!(arr.cols, 2);
                assert_eq!(arr.data, vec!['a', 'b', 'a', 'c']);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![2.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 1.0, 2.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_string_elements_stable() {
        let array = StringArray::new(
            vec!["beta".into(), "alpha".into(), "beta".into()],
            vec![3, 1],
        )
        .unwrap();
        let eval =
            evaluate_sync(Value::StringArray(array), &[Value::from("stable")]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::StringArray(sa) => {
                assert_eq!(sa.data, vec!["beta", "alpha"]);
                assert_eq!(sa.shape, vec![2, 1]);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 2.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 2.0, 1.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_string_rows() {
        let array = StringArray::new(
            vec![
                "alpha".into(),
                "alpha".into(),
                "gamma".into(),
                "beta".into(),
                "beta".into(),
                "beta".into(),
            ],
            vec![3, 2],
        )
        .unwrap();
        let eval = evaluate_sync(
            Value::StringArray(array),
            &[Value::from("rows"), Value::from("stable")],
        )
        .expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::StringArray(sa) => {
                assert_eq!(sa.shape, vec![2, 2]);
                assert_eq!(sa.data, vec!["alpha", "gamma", "beta", "beta"]);
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 3.0]),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert_eq!(t.data, vec![1.0, 1.0, 2.0]),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_complex_sorted() {
        let tensor = ComplexTensor::new(
            vec![(1.0, 1.0), (0.0, 2.0), (1.0, -1.0), (0.0, 2.0)],
            vec![4, 1],
        )
        .unwrap();
        let eval = evaluate_sync(Value::ComplexTensor(tensor), &[]).expect("unique");
        let (values, ..) = eval.into_triple();
        match values {
            Value::ComplexTensor(t) => {
                assert_eq!(t.data.len(), 3);
                assert_eq!(t.data[0], (1.0, -1.0));
                assert_eq!(t.data[1], (1.0, 1.0));
                assert_eq!(t.data[2], (0.0, 2.0));
            }
            other => panic!("unexpected values {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_handles_logical_arrays() {
        let logical = LogicalArray::new(vec![1, 0, 1, 1], vec![4, 1]).unwrap();
        let eval = evaluate_sync(Value::LogicalArray(logical), &[]).expect("unique");
        let values = eval.into_values_value();
        match values {
            Value::Tensor(t) => assert_eq!(t.data, vec![0.0, 1.0]),
            other => panic!("unexpected values {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_gpu_roundtrip() {
        test_support::with_test_provider(|provider| {
            let tensor = Tensor::new(vec![5.0, 3.0, 5.0, 1.0], vec![4, 1]).unwrap();
            let view = runmat_accelerate_api::HostTensorView {
                data: &tensor.data,
                shape: &tensor.shape,
            };
            let handle = provider.upload(&view).expect("upload");
            let eval =
                evaluate_sync(Value::GpuTensor(handle), &[Value::from("stable")]).expect("unique");
            let values = eval.into_values_value();
            match values {
                Value::Tensor(t) => assert_eq!(t.data, vec![5.0, 3.0, 1.0]),
                other => panic!("unexpected values {other:?}"),
            }
        });
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    #[cfg(feature = "wgpu")]
    fn unique_wgpu_matches_cpu() {
        let _ = runmat_accelerate::backend::wgpu::provider::register_wgpu_provider(
            runmat_accelerate::backend::wgpu::provider::WgpuProviderOptions::default(),
        );
        let tensor = Tensor::new(vec![5.0, 3.0, 5.0, 1.0, 2.0], vec![5, 1]).unwrap();
        let host_eval = evaluate_sync(Value::Tensor(tensor.clone()), &[]).expect("host unique");
        let (host_values, host_ia, host_ic) = host_eval.into_triple();

        let provider = runmat_accelerate_api::provider().expect("provider registered");
        let view = runmat_accelerate_api::HostTensorView {
            data: &tensor.data,
            shape: &tensor.shape,
        };
        let handle = provider.upload(&view).expect("upload");
        let gpu_eval = evaluate_sync(Value::GpuTensor(handle.clone()), &[]).expect("gpu unique");
        let (gpu_values, gpu_ia, gpu_ic) = gpu_eval.into_triple();
        let _ = provider.free(&handle);

        let host_values = test_support::gather(host_values).expect("gather host values");
        let host_ia = test_support::gather(host_ia).expect("gather host ia");
        let host_ic = test_support::gather(host_ic).expect("gather host ic");
        let gpu_values = test_support::gather(gpu_values).expect("gather gpu values");
        let gpu_ia = test_support::gather(gpu_ia).expect("gather gpu ia");
        let gpu_ic = test_support::gather(gpu_ic).expect("gather gpu ic");

        assert_eq!(gpu_values.shape, host_values.shape);
        assert_eq!(gpu_values.data, host_values.data);
        assert_eq!(gpu_ia.data, host_ia.data);
        assert_eq!(gpu_ic.data, host_ic.data);
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_rejects_legacy_option() {
        let tensor = Tensor::new(vec![1.0, 1.0], vec![2, 1]).unwrap();
        let err = error_message(
            evaluate_sync(Value::Tensor(tensor), &[Value::from("legacy")]).unwrap_err(),
        );
        assert!(err.contains("legacy"));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_conflicting_order_flags() {
        let tensor = Tensor::new(vec![1.0, 2.0], vec![2, 1]).unwrap();
        let err = error_message(
            evaluate_sync(
                Value::Tensor(tensor),
                &[Value::from("stable"), Value::from("sorted")],
            )
            .unwrap_err(),
        );
        assert!(err.contains("stable"));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_conflicting_occurrence_flags() {
        let tensor = Tensor::new(vec![1.0, 2.0], vec![2, 1]).unwrap();
        let err = error_message(
            evaluate_sync(
                Value::Tensor(tensor),
                &[Value::from("first"), Value::from("last")],
            )
            .unwrap_err(),
        );
        assert!(err.contains("first"));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_rows_requires_two_dimensional_input() {
        let tensor = Tensor::new(vec![1.0, 2.0], vec![2, 1, 1]).unwrap();
        let err = error_message(
            evaluate_sync(Value::Tensor(tensor), &[Value::from("rows")]).unwrap_err(),
        );
        assert!(err.contains("2-D matrix"));
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_handles_empty_rows() {
        let tensor = Tensor::new(Vec::new(), vec![0, 3]).unwrap();
        let eval = evaluate_sync(Value::Tensor(tensor), &[Value::from("rows")]).expect("unique");
        let (values, ia, ic) = eval.into_triple();
        match values {
            Value::Tensor(t) => {
                assert_eq!(t.shape, vec![0, 3]);
                assert!(t.data.is_empty());
            }
            other => panic!("unexpected values {other:?}"),
        }
        match ia {
            Value::Tensor(t) => assert!(t.data.is_empty()),
            other => panic!("unexpected IA {other:?}"),
        }
        match ic {
            Value::Tensor(t) => assert!(t.data.is_empty()),
            other => panic!("unexpected IC {other:?}"),
        }
    }

    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
    #[test]
    fn unique_accepts_integer_scalars() {
        let eval = evaluate_sync(Value::Int(IntValue::I32(42)), &[]).expect("unique");
        let values = eval.into_values_value();
        match values {
            Value::Num(n) => assert_eq!(n, 42.0),
            other => panic!("unexpected values {other:?}"),
        }
    }
}