diff --git a/grep.json b/grep.json
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+++ b/grep.json
@@ -0,0 +1,251 @@
+{
+ "#": [
+ "JSON doesn't allow for multi-line strings, so all outputs are presented ",
+ "here as arrays of strings. It's up to the test generator to join the ",
+ "lines together with line breaks.",
+ "",
+ "The tests are divided into two groups: ",
+ "* Grepping a single file",
+ "* Grepping multiple files at once",
+ "",
+ "The language track implementing this exercise should",
+ "ensure that when the tests run, three files are created",
+ "with the following contents. The file names and their",
+ "contents are listed in the 'files' section below."
+ ],
+ "files": [
+ {
+ "name": "iliad.txt",
+ "contents": [
+ "Achilles sing, O Goddess! Peleus' son;",
+ "His wrath pernicious, who ten thousand woes",
+ "Caused to Achaia's host, sent many a soul",
+ "Illustrious into Ades premature,",
+ "And Heroes gave (so stood the will of Jove)",
+ "To dogs and to all ravening fowls a prey,",
+ "When fierce dispute had separated once",
+ "The noble Chief Achilles from the son",
+ "Of Atreus, Agamemnon, King of men."
+ ]
+ },
+ {
+ "name": "midsummer-night.txt",
+ "contents": [
+ "I do entreat your grace to pardon me.",
+ "I know not by what power I am made bold,",
+ "Nor how it may concern my modesty,",
+ "In such a presence here to plead my thoughts;",
+ "But I beseech your grace that I may know",
+ "The worst that may befall me in this case,",
+ "If I refuse to wed Demetrius."
+ ]
+ },
+ {
+ "name": "paradise-lost.txt",
+ "contents": [
+ "Of Mans First Disobedience, and the Fruit",
+ "Of that Forbidden Tree, whose mortal tast",
+ "Brought Death into the World, and all our woe,",
+ "With loss of Eden, till one greater Man",
+ "Restore us, and regain the blissful Seat,",
+ "Sing Heav'nly Muse, that on the secret top",
+ "Of Oreb, or of Sinai, didst inspire",
+ "That Shepherd, who first taught the chosen Seed"
+ ]
+ }
+ ],
+ "single-file": {
+ "description": ["Test grepping a single file"],
+ "cases": [
+ {
+ "description": "One file, one match, no flags",
+ "pattern": "Agamemnon",
+ "flags": [],
+ "files": ["iliad.txt"],
+ "expected": [
+ "Of Atreus, Agamemnon, King of men."
+ ]
+ },
+ {
+ "description": "One file, several matches, no flags",
+ "pattern": "may",
+ "flags": [],
+ "files": ["midsummer-night.txt"],
+ "expected": [
+ "Nor how it may concern my modesty,",
+ "But I beseech your grace that I may know",
+ "The worst that may befall me in this case,"
+ ]
+ },
+ {
+ "description": "One file, several matches, print line numbers flag",
+ "pattern": "may",
+ "flags": ["-n"],
+ "files": ["midsummer-night.txt"],
+ "expected": [
+ "3:Nor how it may concern my modesty,",
+ "5:But I beseech your grace that I may know",
+ "6:The worst that may befall me in this case,"
+ ]
+ },
+ {
+ "description": "One file, one match, print file names flag",
+ "pattern": "Forbidden",
+ "flags": ["-l"],
+ "files": ["paradise-lost.txt"],
+ "expected": [
+ "paradise-lost.txt"
+ ]
+ },
+ {
+ "description": "One file, several matches, case-insensitive flag",
+ "pattern": "ACHILLES",
+ "flags": ["-i"],
+ "files": ["iliad.txt"],
+ "expected": [
+ "Achilles sing, O Goddess! Peleus' son;",
+ "The noble Chief Achilles from the son"
+ ]
+ },
+ {
+ "description": "One file, several matches, inverted flag",
+ "pattern": "Of",
+ "flags": ["-v"],
+ "files": ["paradise-lost.txt"],
+ "expected": [
+ "Brought Death into the World, and all our woe,",
+ "With loss of Eden, till one greater Man",
+ "Restore us, and regain the blissful Seat,",
+ "Sing Heav'nly Muse, that on the secret top",
+ "That Shepherd, who first taught the chosen Seed"
+ ]
+ },
+ {
+ "description": "One file, one match, match entire lines flag",
+ "pattern": "With loss of Eden, till one greater Man",
+ "flags": ["-x"],
+ "files": ["paradise-lost.txt"],
+ "expected": [
+ "With loss of Eden, till one greater Man"
+ ]
+ },
+ {
+ "description": "One file, one match, multiple flags",
+ "pattern": "OF ATREUS, Agamemnon, KIng of MEN.",
+ "flags": ["-n", "-i", "-x"],
+ "files": ["iliad.txt"],
+ "expected": [
+ "9:Of Atreus, Agamemnon, King of men."
+ ]
+ },
+ {
+ "description": "One file, no matches, various flags",
+ "pattern": "Gandalf",
+ "flags": ["-n", "-l", "-x", "-i"],
+ "files": ["iliad.txt"],
+ "expected": []
+ }
+ ]
+ },
+ "multiple-files": {
+ "description": ["Test grepping multiples files at once"],
+ "cases": [
+ {
+ "description": "Multiple files, one match, no flags",
+ "pattern": "Agamemnon",
+ "flags": [],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "iliad.txt:Of Atreus, Agamemnon, King of men."
+ ]
+ },
+ {
+ "description": "Multiple files, several matches, no flags",
+ "pattern": "may",
+ "flags": [],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "midsummer-night.txt:Nor how it may concern my modesty,",
+ "midsummer-night.txt:But I beseech your grace that I may know",
+ "midsummer-night.txt:The worst that may befall me in this case,"
+ ]
+ },
+ {
+ "description": "Multiple files, several matches, print line numbers flag",
+ "pattern": "that",
+ "flags": ["-n"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "midsummer-night.txt:5:But I beseech your grace that I may know",
+ "midsummer-night.txt:6:The worst that may befall me in this case,",
+ "paradise-lost.txt:2:Of that Forbidden Tree, whose mortal tast",
+ "paradise-lost.txt:6:Sing Heav'nly Muse, that on the secret top"
+ ]
+ },
+ {
+ "description": "Multiple files, one match, print file names flag",
+ "pattern": "who",
+ "flags": ["-l"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "iliad.txt",
+ "paradise-lost.txt"
+ ]
+ },
+ {
+ "description": "Multiple files, several matches, case-insensitive flag",
+ "pattern": "TO",
+ "flags": ["-i"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "iliad.txt:Caused to Achaia's host, sent many a soul",
+ "iliad.txt:Illustrious into Ades premature,",
+ "iliad.txt:And Heroes gave (so stood the will of Jove)",
+ "iliad.txt:To dogs and to all ravening fowls a prey,",
+ "midsummer-night.txt:I do entreat your grace to pardon me.",
+ "midsummer-night.txt:In such a presence here to plead my thoughts;",
+ "midsummer-night.txt:If I refuse to wed Demetrius.",
+ "paradise-lost.txt:Brought Death into the World, and all our woe,",
+ "paradise-lost.txt:Restore us, and regain the blissful Seat,",
+ "paradise-lost.txt:Sing Heav'nly Muse, that on the secret top"
+ ]
+ },
+ {
+ "description": "Multiple files, several matches, inverted flag",
+ "pattern": "a",
+ "flags": ["-v"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "iliad.txt:Achilles sing, O Goddess! Peleus' son;",
+ "iliad.txt:The noble Chief Achilles from the son",
+ "midsummer-night.txt:If I refuse to wed Demetrius."
+ ]
+ },
+ {
+ "description": "Multiple files, one match, match entire lines flag",
+ "pattern": "But I beseech your grace that I may know",
+ "flags": ["-x"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "midsummer-night.txt:But I beseech your grace that I may know"
+ ]
+ },
+ {
+ "description": "Multiple files, one match, multiple flags",
+ "pattern": "WITH LOSS OF EDEN, TILL ONE GREATER MAN",
+ "flags": ["-n", "-i", "-x"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": [
+ "paradise-lost.txt:4:With loss of Eden, till one greater Man"
+ ]
+ },
+ {
+ "description": "Multiple files, no matches, various flags",
+ "pattern": "Frodo",
+ "flags": ["-n", "-l", "-x", "-i"],
+ "files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
+ "expected": []
+ }
+ ]
+ }
+}
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diff --git a/grep.md b/grep.md
index 266f4a28ea..37fa8bdb27 100644
--- a/grep.md
+++ b/grep.md
@@ -1,25 +1,60 @@
-Given a string `filename` and regular expression `pattern`, collect and
-return the line numbers and contents of all lines in the file denoted by
-`filename` that match `pattern`.
-
-In other words, solutions should open the file described by `filename`
-and read each of its lines while keeping track of line numbers (starting at 1).
-If a line matches `pattern`, create a pair containing the line's
-number and the line itself.
-After reading the entire file, return a list of all such pairs sorted
-from lowest line number to highest.
-
-The name "grep" comes from the [Unix program](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html) with the same name.
-(In Unix, "grep" was a mnemonic for a useful command to another program [sed](http://www.gnu.org/software/sed/manual/sed.html), whose name means "stream editor".)
-
-The Unix `grep` can be run from the command line and accepts a variety of flags.
-Try reproducing some of these in your implementation. For example:
-- Accept a pattern and list of files on the command-line, print results
- for each file to the console.
-- Implement the flags:
- - `-l` Print only the names of files that contain at least one matching line.
- - `-v` Invert the program -- collect all lines that fail to match the pattern.
- - `-x` Only match entire lines, instead of lines that contain a match.
-- Support multiple flags at once.
- For example, running `grep -l -x "hello" file1.txt file2.txt` should
- print the names of files that do not contain the string "hello"
+The Unix [`grep`](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html) command can be used to search for lines in one or more files
+that match a user-provided search query (known as the *pattern*).
+
+The `grep` command takes three arguments:
+
+1. The pattern used to match lines in a file.
+2. Zero or more flags to customize the matching behavior.
+3. One or more files in which to search for matching lines.
+
+Your task is to implement the `grep` function, which should read the contents
+of the specified files, find the lines that match the specified pattern
+and then output those lines as a single string. Note that the lines should
+be output in the order in which they were found, with the first matching line
+in the first file being output first.
+
+As an example, suppose there is a file named "input.txt" with the following contents:
+
+
+hello
+world
+hello again
+
+
+If we were to call `grep "hello" input.txt`, the returned string should be:
+
+
+hello
+hello again
+
+
+### Flags
+
+As said earlier, the `grep` command should also support the following flags:
+
+- `-n` Print the line numbers of each matching line.
+- `-l` Print only the names of files that contain at least one matching line.
+- `-i` Match line using a case-insensitive comparison.
+- `-v` Invert the program -- collect all lines that fail to match the pattern.
+- `-x` Only match entire lines, instead of lines that contain a match.
+
+If we run `grep -n "hello" input.txt`, the `-n` flag will require the matching
+lines to be prefixed with its line number:
+
+
+1:hello
+3:hello again
+
+
+And if we run `grep -i "HELLO" input.txt`, we'll do a case-insensitive match,
+and the output will be:
+
+
+hello
+hello again
+
+
+The `grep` command should support multiple flags at once.
+
+For example, running `grep -l -v "hello" file1.txt file2.txt` should
+print the names of files that do not contain the string "hello".
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