Skip to main content

runmat_runtime/builtins/strings/core/
char.rs

1//! MATLAB-compatible `char` builtin with GPU-aware conversion semantics for RunMat.
2
3use runmat_builtins::{
4    BuiltinCompletionPolicy, BuiltinDescriptor, BuiltinErrorDescriptor, BuiltinOutputMode,
5    BuiltinParamArity, BuiltinParamDescriptor, BuiltinParamType, BuiltinSignatureDescriptor,
6    CellArray, CharArray, LogicalArray, SparseTensor, StringArray, Tensor, Value,
7};
8use runmat_macros::runtime_builtin;
9
10use crate::builtins::common::map_control_flow_with_builtin;
11use crate::builtins::common::spec::{
12    BroadcastSemantics, BuiltinFusionSpec, BuiltinGpuSpec, ConstantStrategy, GpuOpKind,
13    ReductionNaN, ResidencyPolicy, ShapeRequirements,
14};
15use crate::builtins::strings::type_resolvers::string_array_type;
16use crate::{build_runtime_error, gather_if_needed_async, BuiltinResult, RuntimeError};
17
18#[runmat_macros::register_gpu_spec(builtin_path = "crate::builtins::strings::core::char")]
19pub const GPU_SPEC: BuiltinGpuSpec = BuiltinGpuSpec {
20    name: "char",
21    op_kind: GpuOpKind::Custom("conversion"),
22    supported_precisions: &[],
23    broadcast: BroadcastSemantics::None,
24    provider_hooks: &[],
25    constant_strategy: ConstantStrategy::InlineLiteral,
26    residency: ResidencyPolicy::GatherImmediately,
27    nan_mode: ReductionNaN::Include,
28    two_pass_threshold: None,
29    workgroup_size: None,
30    accepts_nan_mode: false,
31    notes:
32        "Conversion always runs on the CPU; GPU tensors are gathered before building the result.",
33};
34
35#[runmat_macros::register_fusion_spec(builtin_path = "crate::builtins::strings::core::char")]
36pub const FUSION_SPEC: BuiltinFusionSpec = BuiltinFusionSpec {
37    name: "char",
38    shape: ShapeRequirements::Any,
39    constant_strategy: ConstantStrategy::InlineLiteral,
40    elementwise: None,
41    reduction: None,
42    emits_nan: false,
43    notes: "Character materialisation runs outside of fusion; results always live on the host.",
44};
45
46const BUILTIN_NAME: &str = "char";
47const CHAR_SPARSE_DENSE_ELEMENT_LIMIT: usize = 10_000_000;
48
49const CHAR_OUTPUT: [BuiltinParamDescriptor; 1] = [BuiltinParamDescriptor {
50    name: "C",
51    ty: BuiltinParamType::Any,
52    arity: BuiltinParamArity::Required,
53    default: None,
54    description: "Character array result.",
55}];
56
57const CHAR_INPUT_SINGLE: [BuiltinParamDescriptor; 1] = [BuiltinParamDescriptor {
58    name: "X",
59    ty: BuiltinParamType::Any,
60    arity: BuiltinParamArity::Required,
61    default: None,
62    description: "Input value to convert into character data.",
63}];
64
65const CHAR_INPUT_VARIADIC: [BuiltinParamDescriptor; 1] = [BuiltinParamDescriptor {
66    name: "X...",
67    ty: BuiltinParamType::Any,
68    arity: BuiltinParamArity::Variadic,
69    default: None,
70    description: "Multiple inputs converted row-wise and padded.",
71}];
72
73const CHAR_SIGNATURES: [BuiltinSignatureDescriptor; 3] = [
74    BuiltinSignatureDescriptor {
75        label: "C = char()",
76        inputs: &[],
77        outputs: &CHAR_OUTPUT,
78    },
79    BuiltinSignatureDescriptor {
80        label: "C = char(X)",
81        inputs: &CHAR_INPUT_SINGLE,
82        outputs: &CHAR_OUTPUT,
83    },
84    BuiltinSignatureDescriptor {
85        label: "C = char(X...)",
86        inputs: &CHAR_INPUT_VARIADIC,
87        outputs: &CHAR_OUTPUT,
88    },
89];
90
91const CHAR_ERROR_INVALID_INPUT: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
92    code: "RM.CHAR.INVALID_INPUT",
93    identifier: Some("RunMat:char:InvalidInput"),
94    when: "Input type cannot be converted to character data.",
95    message: "char: invalid input",
96};
97
98const CHAR_ERROR_INVALID_CODEPOINT: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
99    code: "RM.CHAR.INVALID_CODEPOINT",
100    identifier: Some("RunMat:char:InvalidCodePoint"),
101    when: "Numeric input is not a finite integer Unicode code point.",
102    message: "char: numeric inputs must be finite Unicode code points",
103};
104
105const CHAR_ERROR_DIMENSION: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
106    code: "RM.CHAR.INVALID_DIMENSION",
107    identifier: Some("RunMat:char:InvalidDimension"),
108    when: "Array inputs are not 2-D (or trailing singleton dimensions).",
109    message: "char: inputs must be 2-D",
110};
111
112const CHAR_ERROR_INTERNAL: BuiltinErrorDescriptor = BuiltinErrorDescriptor {
113    code: "RM.CHAR.INTERNAL",
114    identifier: Some("RunMat:char:InternalError"),
115    when: "Internal character array construction failed.",
116    message: "char: internal error",
117};
118
119const CHAR_ERRORS: [BuiltinErrorDescriptor; 4] = [
120    CHAR_ERROR_INVALID_INPUT,
121    CHAR_ERROR_INVALID_CODEPOINT,
122    CHAR_ERROR_DIMENSION,
123    CHAR_ERROR_INTERNAL,
124];
125
126pub const CHAR_DESCRIPTOR: BuiltinDescriptor = BuiltinDescriptor {
127    signatures: &CHAR_SIGNATURES,
128    output_mode: BuiltinOutputMode::Fixed,
129    completion_policy: BuiltinCompletionPolicy::Public,
130    errors: &CHAR_ERRORS,
131};
132
133fn char_error(error: &'static BuiltinErrorDescriptor) -> RuntimeError {
134    char_error_with_message(error.message, error)
135}
136
137fn char_error_with_message(
138    message: impl Into<String>,
139    error: &'static BuiltinErrorDescriptor,
140) -> RuntimeError {
141    let mut builder = build_runtime_error(message).with_builtin(BUILTIN_NAME);
142    if let Some(identifier) = error.identifier {
143        builder = builder.with_identifier(identifier);
144    }
145    builder.build()
146}
147
148fn char_flow(message: impl Into<String>) -> RuntimeError {
149    char_error_with_message(message, &CHAR_ERROR_INTERNAL)
150}
151
152fn remap_char_flow(err: RuntimeError) -> RuntimeError {
153    map_control_flow_with_builtin(err, BUILTIN_NAME)
154}
155
156#[runtime_builtin(
157    name = "char",
158    category = "strings/core",
159    summary = "Convert numeric codes and text values into character arrays.",
160    keywords = "char,character,string,gpu",
161    accel = "conversion",
162    type_resolver(string_array_type),
163    descriptor(crate::builtins::strings::core::char::CHAR_DESCRIPTOR),
164    builtin_path = "crate::builtins::strings::core::char"
165)]
166async fn char_builtin(rest: Vec<Value>) -> crate::BuiltinResult<Value> {
167    if rest.is_empty() {
168        let empty =
169            CharArray::new(Vec::new(), 0, 0).map_err(|_| char_error(&CHAR_ERROR_INTERNAL))?;
170        return Ok(Value::CharArray(empty));
171    }
172
173    let mut rows: Vec<Vec<char>> = Vec::new();
174    let mut max_width = 0usize;
175
176    for arg in rest {
177        let gathered = gather_if_needed_async(&arg)
178            .await
179            .map_err(remap_char_flow)?;
180        let mut produced = value_to_char_rows(&gathered)?;
181        for row in &produced {
182            if row.len() > max_width {
183                max_width = row.len();
184            }
185        }
186        rows.append(&mut produced);
187    }
188
189    if rows.is_empty() {
190        let empty =
191            CharArray::new(Vec::new(), 0, 0).map_err(|_| char_error(&CHAR_ERROR_INTERNAL))?;
192        return Ok(Value::CharArray(empty));
193    }
194
195    let cols = max_width;
196    let total_rows = rows.len();
197    let mut data = vec![' '; total_rows * cols];
198    for (row_idx, row) in rows.into_iter().enumerate() {
199        for (col_idx, ch) in row.into_iter().enumerate() {
200            if col_idx < cols {
201                data[row_idx * cols + col_idx] = ch;
202            }
203        }
204    }
205
206    let array =
207        CharArray::new(data, total_rows, cols).map_err(|_| char_error(&CHAR_ERROR_INTERNAL))?;
208    Ok(Value::CharArray(array))
209}
210
211fn value_to_char_rows(value: &Value) -> BuiltinResult<Vec<Vec<char>>> {
212    if let Some(array) = crate::builtins::datetime::datetime_char_array(value)
213        .map_err(|err| char_flow(err.message().to_string()))?
214    {
215        return Ok(char_array_rows(&array));
216    }
217    if let Some(array) = crate::builtins::duration::duration_char_array(value)
218        .map_err(|err| char_flow(err.message().to_string()))?
219    {
220        return Ok(char_array_rows(&array));
221    }
222    match value {
223        Value::CharArray(ca) => Ok(char_array_rows(ca)),
224        Value::String(s) => Ok(vec![s.chars().collect()]),
225        Value::StringArray(sa) => string_array_rows(sa),
226        Value::Num(n) => Ok(vec![vec![number_to_char(*n)?]]),
227        Value::Int(i) => {
228            let as_double = i.to_f64();
229            Ok(vec![vec![number_to_char(as_double)?]])
230        }
231        Value::Bool(b) => {
232            let code = if *b { 1.0 } else { 0.0 };
233            Ok(vec![vec![number_to_char(code)?]])
234        }
235        Value::Tensor(t) => tensor_rows(t),
236        Value::SparseTensor(s) => {
237            ensure_sparse_dense_conversion(s)?;
238            let dense = s.to_dense().map_err(char_flow)?;
239            tensor_rows(&dense)
240        }
241        Value::LogicalArray(la) => logical_rows(la),
242        Value::Cell(ca) => cell_rows(ca),
243        Value::GpuTensor(_) => Err(char_error(&CHAR_ERROR_INVALID_INPUT)),
244        Value::Complex(_, _) | Value::ComplexTensor(_) => Err(char_error_with_message(
245            "char: complex inputs are not supported",
246            &CHAR_ERROR_INVALID_INPUT,
247        )),
248        Value::Struct(_)
249        | Value::Object(_)
250        | Value::HandleObject(_)
251        | Value::Listener(_)
252        | Value::FunctionHandle(_)
253        | Value::ExternalFunctionHandle(_)
254        | Value::MethodFunctionHandle(_)
255        | Value::BoundFunctionHandle { .. }
256        | Value::Closure(_)
257        | Value::ClassRef(_)
258        | Value::MException(_)
259        | Value::OutputList(_) => Err(char_error_with_message(
260            format!("char: unsupported input type {:?}", value),
261            &CHAR_ERROR_INVALID_INPUT,
262        )),
263    }
264}
265
266fn char_array_rows(ca: &CharArray) -> Vec<Vec<char>> {
267    let mut rows = Vec::with_capacity(ca.rows);
268    for r in 0..ca.rows {
269        let mut row = Vec::with_capacity(ca.cols);
270        for c in 0..ca.cols {
271            row.push(ca.data[r * ca.cols + c]);
272        }
273        rows.push(row);
274    }
275    rows
276}
277
278fn string_array_rows(sa: &StringArray) -> BuiltinResult<Vec<Vec<char>>> {
279    ensure_two_dimensional(&sa.shape, "char")?;
280    if sa.data.is_empty() {
281        return Ok(Vec::new());
282    }
283    let mut rows = Vec::with_capacity(sa.data.len());
284    let rows_count = sa.rows();
285    let cols_count = sa.cols();
286    if rows_count == 0 || cols_count == 0 {
287        return Ok(Vec::new());
288    }
289    for c in 0..cols_count {
290        for r in 0..rows_count {
291            let idx = r + c * rows_count;
292            rows.push(sa.data[idx].chars().collect());
293        }
294    }
295    Ok(rows)
296}
297
298fn tensor_rows(t: &Tensor) -> BuiltinResult<Vec<Vec<char>>> {
299    ensure_two_dimensional(&t.shape, "char")?;
300    let (rows, cols) = infer_rows_cols(&t.shape, t.data.len());
301    if rows == 0 {
302        return Ok(Vec::new());
303    }
304    let mut out = Vec::with_capacity(rows);
305    for r in 0..rows {
306        let mut row = Vec::with_capacity(cols);
307        for c in 0..cols {
308            if cols == 0 {
309                continue;
310            }
311            let idx = r + c * rows;
312            let value = t.data[idx];
313            row.push(number_to_char(value)?);
314        }
315        out.push(row);
316    }
317    Ok(out)
318}
319
320fn logical_rows(la: &LogicalArray) -> BuiltinResult<Vec<Vec<char>>> {
321    ensure_two_dimensional(&la.shape, "char")?;
322    let (rows, cols) = infer_rows_cols(&la.shape, la.data.len());
323    if rows == 0 {
324        return Ok(Vec::new());
325    }
326    let mut out = Vec::with_capacity(rows);
327    for r in 0..rows {
328        let mut row = Vec::with_capacity(cols);
329        for c in 0..cols {
330            if cols == 0 {
331                continue;
332            }
333            let idx = r + c * rows;
334            let code = if la.data[idx] != 0 { 1.0 } else { 0.0 };
335            row.push(number_to_char(code)?);
336        }
337        out.push(row);
338    }
339    Ok(out)
340}
341
342fn cell_rows(ca: &CellArray) -> BuiltinResult<Vec<Vec<char>>> {
343    let mut rows = Vec::with_capacity(ca.data.len());
344    for ptr in &ca.data {
345        let element = (**ptr).clone();
346        let mut converted = value_to_char_rows(&element)?;
347        match converted.len() {
348            0 => rows.push(Vec::new()),
349            1 => rows.push(converted.remove(0)),
350            _ => {
351                return Err(char_error_with_message(
352                    "char: cell elements must be character vectors or string scalars",
353                    &CHAR_ERROR_INVALID_INPUT,
354                ))
355            }
356        }
357    }
358    Ok(rows)
359}
360
361fn ensure_sparse_dense_conversion(sparse: &SparseTensor) -> BuiltinResult<()> {
362    let total_elements = sparse.rows.checked_mul(sparse.cols).ok_or_else(|| {
363        char_error_with_message(
364            "char: sparse matrix dimensions overflow",
365            &CHAR_ERROR_INVALID_INPUT,
366        )
367    })?;
368    if total_elements > CHAR_SPARSE_DENSE_ELEMENT_LIMIT {
369        return Err(char_error_with_message(
370            format!(
371                "char: cannot convert sparse tensor {}x{} with {} stored entries to dense character array ({} elements exceeds safe threshold)",
372                sparse.rows,
373                sparse.cols,
374                sparse.nnz(),
375                total_elements
376            ),
377            &CHAR_ERROR_INVALID_INPUT,
378        ));
379    }
380    Ok(())
381}
382
383fn number_to_char(value: f64) -> BuiltinResult<char> {
384    if !value.is_finite() {
385        return Err(char_error_with_message(
386            "char: numeric inputs must be finite",
387            &CHAR_ERROR_INVALID_CODEPOINT,
388        ));
389    }
390    let rounded = value.round();
391    if (value - rounded).abs() > 1e-9 {
392        return Err(char_error_with_message(
393            format!("char: numeric inputs must be integers in the Unicode range (got {value})"),
394            &CHAR_ERROR_INVALID_CODEPOINT,
395        ));
396    }
397    if rounded < 0.0 {
398        return Err(char_error_with_message(
399            format!("char: negative code points are invalid (got {rounded})"),
400            &CHAR_ERROR_INVALID_CODEPOINT,
401        ));
402    }
403    if rounded > 0x10FFFF as f64 {
404        return Err(char_error_with_message(
405            format!("char: code point {} exceeds Unicode range", rounded as u64),
406            &CHAR_ERROR_INVALID_CODEPOINT,
407        ));
408    }
409    let code = rounded as u32;
410    char::from_u32(code).ok_or_else(|| {
411        char_error_with_message(
412            format!("char: invalid code point {code}"),
413            &CHAR_ERROR_INVALID_CODEPOINT,
414        )
415    })
416}
417
418fn ensure_two_dimensional(shape: &[usize], context: &str) -> BuiltinResult<()> {
419    if shape.len() <= 2 {
420        return Ok(());
421    }
422    if shape.iter().skip(2).all(|&d| d == 1) {
423        return Ok(());
424    }
425    Err(char_error_with_message(
426        format!("{context}: inputs must be 2-D"),
427        &CHAR_ERROR_DIMENSION,
428    ))
429}
430
431fn infer_rows_cols(shape: &[usize], len: usize) -> (usize, usize) {
432    match shape.len() {
433        0 => {
434            if len == 0 {
435                (0, 0)
436            } else {
437                (1, 1)
438            }
439        }
440        1 => (1, shape[0]),
441        2 => (shape[0], shape[1]),
442        _ => {
443            let rows = shape[0];
444            let cols = if shape.len() > 1 { shape[1] } else { 1 };
445            (rows, cols)
446        }
447    }
448}
449
450#[cfg(test)]
451pub(crate) mod tests {
452    use super::*;
453    use crate::builtins::common::test_support;
454    use runmat_builtins::{ResolveContext, Type};
455
456    fn char_builtin(rest: Vec<Value>) -> BuiltinResult<Value> {
457        futures::executor::block_on(super::char_builtin(rest))
458    }
459    use runmat_builtins::StringArray;
460
461    fn error_message(err: crate::RuntimeError) -> String {
462        err.message().to_string()
463    }
464
465    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
466    #[test]
467    fn char_no_arguments_returns_empty() {
468        let result = char_builtin(Vec::new()).expect("char");
469        match result {
470            Value::CharArray(ca) => {
471                assert_eq!(ca.rows, 0);
472                assert_eq!(ca.cols, 0);
473                assert!(ca.data.is_empty());
474            }
475            other => panic!("expected char array, got {other:?}"),
476        }
477    }
478
479    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
480    #[test]
481    fn char_from_string_scalar() {
482        let value = Value::String("RunMat".to_string());
483        let result = char_builtin(vec![value]).expect("char");
484        match result {
485            Value::CharArray(ca) => {
486                assert_eq!(ca.rows, 1);
487                assert_eq!(ca.cols, 6);
488                assert_eq!(ca.data, "RunMat".chars().collect::<Vec<_>>());
489            }
490            other => panic!("expected char array, got {other:?}"),
491        }
492    }
493
494    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
495    #[test]
496    fn char_from_numeric_tensor() {
497        let tensor =
498            Tensor::new(vec![82.0, 85.0, 78.0, 77.0, 65.0, 84.0], vec![1, 6]).expect("tensor");
499        let result = char_builtin(vec![Value::Tensor(tensor)]).expect("char");
500        match result {
501            Value::CharArray(ca) => {
502                assert_eq!(ca.rows, 1);
503                assert_eq!(ca.cols, 6);
504                assert_eq!(ca.data, "RUNMAT".chars().collect::<Vec<_>>());
505            }
506            other => panic!("expected char array, got {other:?}"),
507        }
508    }
509
510    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
511    #[test]
512    fn char_from_string_array_with_padding() {
513        let data = vec!["cat".to_string(), "giraffe".to_string()];
514        let sa = StringArray::new(data, vec![2, 1]).expect("string array");
515        let result = char_builtin(vec![Value::StringArray(sa)]).expect("char from string array");
516        match result {
517            Value::CharArray(ca) => {
518                assert_eq!(ca.rows, 2);
519                assert_eq!(ca.cols, 7);
520                assert_eq!(
521                    ca.data,
522                    vec!['c', 'a', 't', ' ', ' ', ' ', ' ', 'g', 'i', 'r', 'a', 'f', 'f', 'e']
523                );
524            }
525            other => panic!("expected char array, got {other:?}"),
526        }
527    }
528
529    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
530    #[test]
531    fn char_from_cell_array_of_strings() {
532        let cell = CellArray::new(
533            vec![
534                Value::from("north"),
535                Value::from("east"),
536                Value::from("west"),
537            ],
538            3,
539            1,
540        )
541        .expect("cell array");
542        let result = char_builtin(vec![Value::Cell(cell)]).expect("char");
543        match result {
544            Value::CharArray(ca) => {
545                assert_eq!(ca.rows, 3);
546                assert_eq!(ca.cols, 5);
547                assert_eq!(
548                    ca.data,
549                    vec!['n', 'o', 'r', 't', 'h', 'e', 'a', 's', 't', ' ', 'w', 'e', 's', 't', ' ']
550                );
551            }
552            other => panic!("expected char array, got {other:?}"),
553        }
554    }
555
556    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
557    #[test]
558    fn char_numeric_and_text_arguments_concatenate() {
559        let text = Value::String("hi".to_string());
560        let codes = Tensor::new(vec![65.0, 66.0], vec![1, 2]).expect("tensor");
561        let result = char_builtin(vec![text, Value::Tensor(codes)]).expect("char");
562        match result {
563            Value::CharArray(ca) => {
564                assert_eq!(ca.rows, 2);
565                assert_eq!(ca.cols, 2);
566                assert_eq!(ca.data, vec!['h', 'i', 'A', 'B']);
567            }
568            other => panic!("expected char array, got {other:?}"),
569        }
570    }
571
572    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
573    #[test]
574    fn char_gpu_tensor_round_trip() {
575        test_support::with_test_provider(|provider| {
576            let tensor = Tensor::new(vec![82.0, 85.0, 78.0], vec![1, 3]).expect("tensor");
577            let view = runmat_accelerate_api::HostTensorView {
578                data: &tensor.data,
579                shape: &tensor.shape,
580            };
581            let handle = provider.upload(&view).expect("upload");
582            let result = char_builtin(vec![Value::GpuTensor(handle)]).expect("char");
583            match result {
584                Value::CharArray(ca) => {
585                    assert_eq!(ca.rows, 1);
586                    assert_eq!(ca.cols, 3);
587                    assert_eq!(ca.data, vec!['R', 'U', 'N']);
588                }
589                other => panic!("expected char array, got {other:?}"),
590            }
591        });
592    }
593
594    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
595    #[test]
596    fn char_rejects_non_integer_numeric() {
597        let err =
598            error_message(char_builtin(vec![Value::Num(65.5)]).expect_err("non-integer numeric"));
599        assert!(err.contains("integers"), "unexpected error message: {err}");
600    }
601
602    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
603    #[test]
604    fn char_rejects_high_dimension_tensor() {
605        let tensor =
606            Tensor::new(vec![65.0, 66.0], vec![1, 1, 2]).expect("tensor construction failed");
607        let err = error_message(
608            char_builtin(vec![Value::Tensor(tensor)]).expect_err("should reject >2D tensor"),
609        );
610        assert!(err.contains("2-D"), "expected dimension error, got {err}");
611    }
612
613    #[test]
614    fn char_rejects_oversized_sparse_tensor_before_densifying() {
615        let sparse = SparseTensor::zeros(CHAR_SPARSE_DENSE_ELEMENT_LIMIT + 1, 1);
616        let err = char_builtin(vec![Value::SparseTensor(sparse)]).unwrap_err();
617
618        assert_eq!(err.identifier(), Some("RunMat:char:InvalidInput"));
619        assert!(err.message().contains("exceeds safe threshold"));
620    }
621
622    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
623    #[test]
624    fn char_string_array_column_major_order() {
625        let data = vec![
626            "c0r0".to_string(),
627            "c0r1".to_string(),
628            "c1r0".to_string(),
629            "c1r1".to_string(),
630        ];
631        let sa = StringArray::new(data, vec![2, 2]).expect("string array");
632        let result = char_builtin(vec![Value::StringArray(sa)]).expect("char");
633        match result {
634            Value::CharArray(ca) => {
635                assert_eq!(ca.rows, 4);
636                assert_eq!(ca.cols, 4);
637                assert_eq!(ca.data, "c0r0c0r1c1r0c1r1".chars().collect::<Vec<char>>());
638            }
639            other => panic!("expected char array, got {other:?}"),
640        }
641    }
642
643    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
644    #[test]
645    fn char_rejects_high_dimension_string_array() {
646        let sa = StringArray::new(vec!["a".to_string(), "b".to_string()], vec![1, 1, 2])
647            .expect("string array");
648        let err = error_message(
649            char_builtin(vec![Value::StringArray(sa)]).expect_err("should reject >2D string array"),
650        );
651        assert!(err.contains("2-D"), "expected dimension error, got {err}");
652    }
653
654    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
655    #[test]
656    fn char_rejects_complex_input() {
657        let err =
658            error_message(char_builtin(vec![Value::Complex(1.0, 2.0)]).expect_err("complex input"));
659        assert!(
660            err.contains("complex"),
661            "expected complex error message, got {err}"
662        );
663    }
664
665    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
666    #[test]
667    #[cfg(feature = "wgpu")]
668    fn char_wgpu_numeric_codes_matches_cpu() {
669        use runmat_accelerate::backend::wgpu::provider::{
670            register_wgpu_provider, WgpuProviderOptions,
671        };
672
673        let _ = register_wgpu_provider(WgpuProviderOptions::default());
674
675        let tensor = Tensor::new(vec![82.0, 85.0, 78.0], vec![1, 3]).unwrap();
676        let cpu = char_builtin(vec![Value::Tensor(tensor.clone())]).expect("char cpu");
677
678        let view = runmat_accelerate_api::HostTensorView {
679            data: &tensor.data,
680            shape: &tensor.shape,
681        };
682        let handle = runmat_accelerate_api::provider()
683            .expect("wgpu provider")
684            .upload(&view)
685            .expect("upload");
686        let gpu = char_builtin(vec![Value::GpuTensor(handle)]).expect("char gpu");
687
688        match (cpu, gpu) {
689            (Value::CharArray(expected), Value::CharArray(actual)) => {
690                assert_eq!(actual, expected);
691            }
692            other => panic!("unexpected results {other:?}"),
693        }
694    }
695
696    #[test]
697    fn char_type_is_string_array() {
698        assert_eq!(
699            string_array_type(&[Type::Num], &ResolveContext::new(Vec::new())),
700            Type::cell_of(Type::String)
701        );
702    }
703}