Per-engine robots context preset (sitemap-spec §13.0)

A construction-time preset selecting one engine's robots product token, status policy and matcher together, so a caller need not know which token a bounded matcher backend accepts. It is a thin wrapper over robots_context(); every axis stays independently overridable by calling that constructor directly.

Usage

robots_context_preset(preset = robots_context_presets())

Arguments

preset

A single preset name; see robots_context_presets(). Defaults to "google".

Value

An object of class sitemapr_robots_context, the same shape robots_context() returns, carrying the expanded axis values plus the preset name.

Details

The preset's values are expanded onto the returned context rather than re-derived at use time, so the result records exactly which product token, policy ruleset and matcher backend the preset selected. The name is retained on $preset for provenance.

A preset selects a robots engine only. It does not select a sitemap ruleset, and no sitemap ruleset selects it (ADR-009 §1): the bridge between the two value sets is this documented preset, never a silent derivation.

Not every preset is runnable on every install. robotstxtr publishes a matcher_availability per backend, and one reporting capability_unavailable decides nothing — a context on it evaluates cleanly but reports every URL as ROBOTS_INDETERMINATE rather than guessing.

See also

robots_context() for the general constructor and validate_sitemap_robots() for the entry point that accepts the result.

Examples

robots_context_preset("google")
#> $product_token
#> [1] "Googlebot"
#> 
#> $policy_ruleset
#> [1] "google"
#> 
#> $matcher_backend
#> [1] "google"
#> 
#> $preset
#> [1] "google"
#> 
#> attr(,"class")
#> [1] "sitemapr_robots_context"

# The EXPANDED values are readable back off the context.
yandex <- robots_context_preset("yandex")
yandex$product_token
#> [1] "Yandex"
yandex$matcher_backend
#> [1] "yandex"