Description
Construct literal double-brace placeholder binding exercises with missing, extra and repeated-key answers and plain-text substitution.
A parser corpus pairs literal input spellings or structured documents with observable parser results or explicitly constructed expectations. Successful parsing, semantic validity, and exact round-trip preservation are separate properties, so test records retain the relevant evidence.
Construct literal double-brace placeholder binding exercises with missing, extra and repeated-key answers and plain-text substitution.
When to use this tool
Use this generator to create reproducible template placeholder binding fixture cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.
How to use the tool and how it works
- Supply templates, bindings, control, count in the field shapes below. Set seed when you need an explicit replay.
- Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
- Read cases. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.
Recognize literal double-brace ASCII identifier placeholders and sample a template with bindings. Control modes remove a used binding, add an unused binding, or do both. Replace known values and report distinct missing, extra, and repeated keys; unknown placeholders remain literal.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| templates | Templates | Required. Array of Text; maximum UTF-16 length 2048.; minimum items 1; maximum items 16. |
| bindings | Bindings | Required. Array of Object; no unknown keys.; minimum items 0; maximum items 16. |
| bindings[].key | Key | Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128. |
| bindings[].value | Value | Required. Text; maximum UTF-16 length 65536. |
| control | Control | Required. Text; one of "none", "missing", "extra", "both". |
| count | Requested count; the mechanics explain whether one draw expands into several returned records. | Required. Safe integer; minimum 1; maximum 32. |
| seed | Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed. | Optional. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| cases | Cases | Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32. |
| cases[].template | Template | Required. Text; maximum UTF-16 length 65536. |
| cases[].bindings | Bindings | Required. Array of Object; no unknown keys.; minimum items 0; maximum items 17. |
| cases[].bindings[].key | Key | Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128. |
| cases[].bindings[].value | Value | Required. Text; maximum UTF-16 length 65536. |
| cases[].rendered | Rendered | Required. Text; maximum UTF-16 length 65536. |
| cases[].missing | Missing | Required. Array of Text; maximum UTF-16 length 65536.; minimum items 0; maximum items 409. |
| cases[].extra | Extra | Required. Array of Text; maximum UTF-16 length 65536.; minimum items 0; maximum items 17. |
| cases[].repeated | Repeated | Required. Array of Text; maximum UTF-16 length 65536.; minimum items 0; maximum items 256. |
| cases[].prettyBindings | Pretty Bindings | Required. Text; maximum UTF-16 length 65536. |
| randomness | Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source. | Required. Object; no unknown keys. |
| randomness.seed | Optional numeric replay seed; normalization and precedence are explained below. | Required. Safe integer. or Null. |
| randomness.source | Source | Required. Text; one of "context", "seed". |
An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.
{
"input": {
"templates": [
"Hi {{name}} {{name}}"
],
"bindings": [
{
"key": "name",
"value": "Ada"
}
],
"control": "none",
"count": 1,
"seed": 42
},
"output": {
"cases": [
{
"template": "Hi {{name}} {{name}}",
"bindings": [
{
"key": "name",
"value": "Ada"
}
],
"rendered": "Hi Ada Ada",
"missing": [],
"extra": [],
"repeated": [
"name"
],
"prettyBindings": "{\n \"name\": \"Ada\"\n}\n"
}
],
"randomness": {
"seed": 42,
"source": "seed"
}
}
}Limitations and assumptions
- Expansion is nonrecursive plain-text substitution. Values are not HTML escaped, and no template code executes. Missing-binding modes require usable placeholders and all expansion budgets are checked.
- A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
- The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.
Alternative or Complementary methods
For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.
References
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