From c93109dc36d2a29904002f9b28451683d6680b87 Mon Sep 17 00:00:00 2001
From: Cole Faust <colefaust@google.com>
Date: Wed, 27 Apr 2022 17:50:55 -0700
Subject: [PATCH] Add implementations for firstword/lastword

Bug: 226974242
Test: ./out/rbcrun ./build/make/tests/run.rbc
Change-Id: Ibb992f42a59212bae48acd55647b2d0872c2f69e
---
 core/product_config.rbc | 17 +++++++++++++++++
 tests/run.rbc           |  9 +++++++++
 2 files changed, 26 insertions(+)

diff --git a/core/product_config.rbc b/core/product_config.rbc
index 52aaf04a04..1941a3240b 100644
--- a/core/product_config.rbc
+++ b/core/product_config.rbc
@@ -605,6 +605,21 @@ def _filter(pattern, text):
                 break
     return res
 
+def _first_word(input):
+    """Equivalent to the GNU make function $(firstword)."""
+    input = __words(input)
+    if len(input) == 0:
+        return ""
+    return input[0]
+
+def _last_word(input):
+    """Equivalent to the GNU make function $(lastword)."""
+    input = __words(input)
+    l = len(input)
+    if l == 0:
+        return ""
+    return input[l-1]
+
 def _dir(paths):
     """Equivalent to the GNU make function $(dir).
 
@@ -862,6 +877,8 @@ rblf = struct(
     filter_out = _filter_out,
     find_and_copy = _find_and_copy,
     findstring = _findstring,
+    first_word = _first_word,
+    last_word = _last_word,
     inherit = _inherit,
     indirect = _indirect,
     mk2rbc_error = _mk2rbc_error,
diff --git a/tests/run.rbc b/tests/run.rbc
index 2d35e85e81..107be0995a 100644
--- a/tests/run.rbc
+++ b/tests/run.rbc
@@ -81,6 +81,15 @@ assert_eq("/foo/baz", rblf.abspath("/foo/bar/../baz"))
 assert_eq(cwd+"/foo/bar "+cwd+"/foo/baz", rblf.abspath("foo/bar foo/baz"))
 assert_eq("/baz", rblf.abspath("/../../../../../../../../../../../../../../../../baz"))
 
+assert_eq("foo", rblf.first_word("foo bar"))
+assert_eq("foo", rblf.first_word(["foo", "bar"]))
+assert_eq("", rblf.first_word(""))
+assert_eq("", rblf.first_word([]))
+assert_eq("bar", rblf.last_word("foo bar"))
+assert_eq("bar", rblf.last_word(["foo", "bar"]))
+assert_eq("", rblf.last_word(""))
+assert_eq("", rblf.last_word([]))
+
 assert_eq(
     ["build/make/tests/board.rbc", "build/make/tests/board_input_vars.rbc"],
     rblf.expand_wildcard("build/make/tests/board*.rbc")