From 2fbfee237c39c47cda15e93e96ef74a16b4bc40d Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Tue, 27 Jan 2015 13:18:34 -0500
Subject: [PATCH] Implement full file lint caching.

---
 R/cache.R | 20 +++++++++++++++++++-
 R/lint.R  | 18 +++++++++++++-----
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/R/cache.R b/R/cache.R
index 08a590234..c541d17e8 100644
--- a/R/cache.R
+++ b/R/cache.R
@@ -34,6 +34,24 @@ save_cache <- function(cache, file, path = getOption("lintr.cache_directory")) {
   save(file = file.path(path, file), envir = cache, list=ls(envir=cache))
 }
 
+cache_file <- function(cache, filename, linters, lints) {
+  assign(envir = cache,
+    x = digest::digest(list(linters, readLines(filename)), algo = "sha1"),
+    value = lints
+  )
+}
+retrieve_file <- function(cache, filename, linters) {
+  key <- digest::digest(list(linters, readLines(filename)), algo = "sha1")
+  if (exists(key, envir = cache)) {
+    get(
+      envir = cache,
+      x = digest::digest(list(linters, readLines(filename)), algo = "sha1")
+      )
+  } else {
+    NULL
+  }
+}
+
 cache_lint <- function(cache, expr, linter, lints) {
   assign(
     envir = cache,
@@ -44,7 +62,7 @@ cache_lint <- function(cache, expr, linter, lints) {
 retrieve_lint <- function(cache, expr, linter, lines) {
   lints <- get(
     envir = cache,
-    x = digest::digest(list(linter, expr$content), algo="sha1"),
+    x = digest::digest(list(linter, expr$content), algo="sha1")
   )
   lints[] <- lapply(lints, function(lint) {
     lint$line_number <- find_new_line(lint$line_number, unname(lint$line), lines)
diff --git a/R/lint.R b/R/lint.R
index b2952a6d8..e24a9ca59 100644
--- a/R/lint.R
+++ b/R/lint.R
@@ -29,8 +29,12 @@ lint <- function(filename, linters = default_linters, cache = FALSE) {
   lints <- list()
   itr <- 0
 
-  if (cache) {
+  if (isTRUE(cache)) {
     lint_cache <- load_cache(filename)
+    lints <- retrieve_file(lint_cache, filename, linters)
+    if (!is.null(lints)) {
+      return(lints)
+    }
   }
 
   for (expr in source_expressions$expressions) {
@@ -54,15 +58,19 @@ lint <- function(filename, linters = default_linters, cache = FALSE) {
   if (inherits(source_expressions$error, "lint")) {
     lints[[itr <- itr + 1L]] <- source_expressions$error
 
-    if (cache) {
+    if (isTRUE(cache)) {
       cache_lint(lint_cache, list(filename=filename, content=""), "error", source_expressions$error)
     }
   }
 
-  if (cache) {
+  lints <- structure(reorder_lints(flatten_lints(lints)), class = "lints")
+
+  if (isTRUE(cache)) {
+    cache_file(lint_cache, filename, linters, lints)
     save_cache(lint_cache, filename)
   }
-  structure(reorder_lints(flatten_lints(lints)), class = "lints")
+
+  lints
 }
 
 reorder_lints <- function(lints) {
@@ -97,7 +105,7 @@ lint_package <- function(path = NULL, relative_path = TRUE, ...) {
     full.names = TRUE)
 
   lints <- flatten_lints(lapply(files,
-      function(file, ...) {
+      function(file) {
         if (interactive()) {
           message(".", appendLF = FALSE)
         }