uf-valence-codegen 0.1.2

Valence schema codegen (caller-supplied roots)
Documentation 
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//! Policy token emission for schema metadata (mirrors valence-macros).

use proc_macro2::TokenStream;
use quote::quote;
use valence_schema_dsl::{ParsedPolicies, ParsedPolicyRules};

/// Emit TokenStream for schema policies (Option<SchemaPolicies>) with leaked evaluators.
pub(super) fn generate_policies_code(policies: Option<&ParsedPolicies>) -> TokenStream {
    let Some(policies) = policies else {
        return quote! { None };
    };

    if !has_any_policy(policies) {
        return quote! { None };
    }

    let read = policy_rules_tokens(policies.read.as_ref());
    let create = policy_rules_tokens(policies.create.as_ref());
    let update = policy_rules_tokens(policies.update.as_ref());
    let delete = policy_rules_tokens(policies.delete.as_ref());

    quote! {
        Some(valence::SchemaPolicies {
            read: #read,
            create: #create,
            update: #update,
            delete: #delete,
        })
    }
}

fn has_any_policy(policies: &ParsedPolicies) -> bool {
    policies.read.is_some()
        || policies.create.is_some()
        || policies.update.is_some()
        || policies.delete.is_some()
}

fn policy_rules_tokens(rules: Option<&ParsedPolicyRules>) -> TokenStream {
    let Some(rules) = rules else {
        return quote! { None };
    };

    let always_allow = policy_rule_vec_tokens(&rules.always_allow);
    let allow = policy_rule_vec_tokens(&rules.allow);
    let block = policy_rule_vec_tokens(&rules.block);
    let always_block = policy_rule_vec_tokens(&rules.always_block);

    quote! {
        Some(valence::SchemaPolicyRules {
            always_allow: #always_allow,
            allow: #allow,
            block: #block,
            always_block: #always_block,
        })
    }
}

fn policy_rule_vec_tokens(values: &[TokenStream]) -> TokenStream {
    if values.is_empty() {
        return quote! { Vec::new() };
    }

    let items: Vec<TokenStream> = values
        .iter()
        .map(|rule| {
            quote! {
                {
                    let rule = #rule;
                    let evaluator: &'static dyn valence::PolicyEvaluator =
                        Box::leak(Box::new(rule.clone()));
                    valence::SchemaPolicyRule {
                        name: evaluator.name().to_string(),
                        description: evaluator.description().map(|desc| desc.to_string()),
                        evaluator: Some(evaluator),
                    }
                }
            }
        })
        .collect();

    quote! { vec![#(#items),*] }
}