JSON

ccalc can encode and decode JSON data using two built-in functions. These functions are available when ccalc is built with the json feature flag.

Requires the json feature:

cargo build --release --features json

Without this flag, calling jsondecode or jsonencode returns an error message explaining how to enable the feature.

Decoding JSON

jsondecode(str) parses a JSON string and returns a ccalc value.

s = jsondecode('{"x": 1, "y": [1, 2, 3]}')
% s is a struct with fields x and y
s.x      % → 1
s.y      % → [1 2 3]  (1×3 matrix row vector)

Type mapping

Arrays containing only numbers (and null values, which become NaN) decode to a Matrix row vector. Arrays with mixed types (numbers, strings, nested objects, etc.) decode to a Cell.

jsondecode('[1, 2, 3]')          % → [1 2 3]  (Matrix)
jsondecode('[1, "two", 3]')      % → {1, 'two', 3}  (Cell)
jsondecode('null')               % → NaN
jsondecode('true')               % → 1

Nested data

Nested JSON objects become nested structs:

data = jsondecode('{"person": {"name": "Alice", "age": 30}}');
data.person.name   % → 'Alice'
data.person.age    % → 30

Reading from a file

Combine with fileread to decode a JSON file:

raw = fileread('data.json');
data = jsondecode(raw);

Encoding JSON

jsonencode(val) encodes a ccalc value to a compact JSON string.

s.x = 1;
s.y = [1 2 3];
jsonencode(s)   % → '{"x":1.0,"y":[1.0,2.0,3.0]}'

Type mapping

Scalar(Inf) and Scalar(-Inf) cannot be represented in JSON and produce an error. Complex, Lambda, and Function values also produce an error.

jsonencode(42)            % → '42.0'
jsonencode('hello')       % → '"hello"'
jsonencode([1 2 3])       % → '[1.0,2.0,3.0]'
jsonencode({1, 'a'})      % → '[1.0,"a"]'

Writing to a file

s.result = 3.14;
fid = fopen('output.json', 'w');
fprintf(fid, '%s\n', jsonencode(s));
fclose(fid);

Roundtrip example

original = '{"name":"Bob","scores":[88,92,75]}';
data = jsondecode(original);
data.name       % → 'Bob'
data.scores     % → [88 92 75]

% Re-encode (field order preserved via IndexMap):
jsonencode(data)
% → '{"name":"Bob","scores":[88.0,92.0,75.0]}'