aconfig: dump --filter: hook up command line args to dump.rs

This is the first step towards teaching dump to (optionally) filter
which flags to print.

A follow-up CL will implement dump::create_filter_predicate.

Bug: 315487153
Test: atest aconfig.test
Change-Id: Ibe0d4ce6563d3b5718fedd3ebfd45fbf5d935b92
diff --git a/tools/aconfig/src/commands.rs b/tools/aconfig/src/commands.rs
index 7ae1219..d8213e0 100644
--- a/tools/aconfig/src/commands.rs
+++ b/tools/aconfig/src/commands.rs
@@ -23,7 +23,7 @@
 use crate::codegen::cpp::generate_cpp_code;
 use crate::codegen::java::generate_java_code;
 use crate::codegen::rust::generate_rust_code;
-use crate::dump::DumpFormat;
+use crate::dump::{DumpFormat, DumpPredicate};
 use crate::protos::{
     ParsedFlagExt, ProtoFlagMetadata, ProtoFlagPermission, ProtoFlagState, ProtoParsedFlag,
     ProtoParsedFlags, ProtoTracepoint,
@@ -282,13 +282,22 @@
 pub fn dump_parsed_flags(
     mut input: Vec<Input>,
     format: DumpFormat,
+    filters: &[&str],
     dedup: bool,
 ) -> Result<Vec<u8>> {
     let individually_parsed_flags: Result<Vec<ProtoParsedFlags>> =
         input.iter_mut().map(|i| i.try_parse_flags()).collect();
     let parsed_flags: ProtoParsedFlags =
         crate::protos::parsed_flags::merge(individually_parsed_flags?, dedup)?;
-    crate::dump::dump_parsed_flags(parsed_flags.parsed_flag.into_iter(), format)
+    let filters: Vec<Box<DumpPredicate>> = if filters.is_empty() {
+        vec![Box::new(|_| true)]
+    } else {
+        filters.iter().map(|f| crate::dump::create_filter_predicate(f)).collect::<Result<Vec<_>>>()?
+    };
+    crate::dump::dump_parsed_flags(
+        parsed_flags.parsed_flag.into_iter().filter(|flag| filters.iter().any(|p| p(flag))),
+        format,
+    )
 }
 
 fn find_unique_package(parsed_flags: &[ProtoParsedFlag]) -> Option<&str> {
@@ -570,6 +579,7 @@
         let bytes = dump_parsed_flags(
             vec![input],
             DumpFormat::Custom("{fully_qualified_name}".to_string()),
+            &[],
             false,
         )
         .unwrap();
@@ -581,7 +591,8 @@
     fn test_dump_textproto_format_dedup() {
         let input = parse_test_flags_as_input();
         let input2 = parse_test_flags_as_input();
-        let bytes = dump_parsed_flags(vec![input, input2], DumpFormat::Textproto, true).unwrap();
+        let bytes =
+            dump_parsed_flags(vec![input, input2], DumpFormat::Textproto, &[], true).unwrap();
         let text = std::str::from_utf8(&bytes).unwrap();
         assert_eq!(crate::test::TEST_FLAGS_TEXTPROTO.trim(), text.trim());
     }
diff --git a/tools/aconfig/src/dump.rs b/tools/aconfig/src/dump.rs
index 410c392..2380468 100644
--- a/tools/aconfig/src/dump.rs
+++ b/tools/aconfig/src/dump.rs
@@ -123,6 +123,13 @@
     output.extend_from_slice(str.as_bytes());
 }
 
+pub type DumpPredicate = dyn Fn(&ProtoParsedFlag) -> bool;
+
+#[allow(unused)]
+pub fn create_filter_predicate(filter: &str) -> Result<Box<DumpPredicate>> {
+    todo!();
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/tools/aconfig/src/main.rs b/tools/aconfig/src/main.rs
index 08e8b97..fcc5ea5 100644
--- a/tools/aconfig/src/main.rs
+++ b/tools/aconfig/src/main.rs
@@ -37,6 +37,11 @@
 
 use commands::{CodegenMode, Input, OutputFile};
 
+const HELP_DUMP_FILTER: &str = r#"
+Limit which flags to output. If multiple --filter arguments are provided, the output will be
+limited to flags that match any of the filters.
+"#;
+
 fn cli() -> Command {
     Command::new("aconfig")
         .subcommand_required(true)
@@ -109,6 +114,7 @@
                         .value_parser(|s: &str| DumpFormat::try_from(s))
                         .default_value("text"),
                 )
+                .arg(Arg::new("filter").long("filter").action(ArgAction::Append).help(HELP_DUMP_FILTER.trim()))
                 .arg(Arg::new("dedup").long("dedup").num_args(0).action(ArgAction::SetTrue))
                 .arg(Arg::new("out").long("out").default_value("-")),
         )
@@ -252,8 +258,13 @@
             let input = open_zero_or_more_files(sub_matches, "cache")?;
             let format = get_required_arg::<DumpFormat>(sub_matches, "format")
                 .context("failed to dump previously parsed flags")?;
+            let filters = sub_matches
+                .get_many::<String>("filter")
+                .unwrap_or_default()
+                .map(String::as_ref)
+                .collect::<Vec<_>>();
             let dedup = get_required_arg::<bool>(sub_matches, "dedup")?;
-            let output = commands::dump_parsed_flags(input, format.clone(), *dedup)?;
+            let output = commands::dump_parsed_flags(input, format.clone(), &filters, *dedup)?;
             let path = get_required_arg::<String>(sub_matches, "out")?;
             write_output_to_file_or_stdout(path, &output)?;
         }