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Merge pull request #11 from workanator/master
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Ability to inject environment variables into the config file.
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@filipegoncalves
filipegoncalves committed Nov 15, 2015
2 parents ee7b4b8 + 0cdaf11 commit 1e876ab
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Showing 2 changed files with 214 additions and 4 deletions.
30 changes: 30 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,36 @@
//! See the integration tests (in the `tests/` directory) for sample use cases and more complex
//! examples.
//!
//!# Environment variables
//!
//! The crate has an ability to inject environment variables into the configuration file. That
//! becomes possible using special syntax:
//!
//! * `$"SOME_ENV_VAR_NAME"::str` to inject the environment variables `SOME_ENV_VAR_NAME` as the string value.
//! No additiocal changes are made ot the value.
//! * `$"SOME_ENV_VAR_NAME"::bool` to inject the environment variables `SOME_ENV_VAR_NAME` as the boolean value.
//! The value `true` or `yes` or `on` or `1` are converted into `true` otherwise into `false`.
//! * `$"SOME_ENV_VAR_NAME"::int` to inject the environment variables `SOME_ENV_VAR_NAME` as the integer value.
//! The successfully parsed value is injected as `i32` or `i64`, depending on the format, otherwise `0i32` is injected.
//! * `$"SOME_ENV_VAR_NAME"::flt` to inject the environment variables `SOME_ENV_VAR_NAME` as the floating value.
//! The successfully parsed value is injected as `f32` or `f64`, depending on the format, otherwise `0f32` is injected.
//!
//!
//! **Example**:
//!
//! ```ignore
//! #!/bin/sh
//! export LOG_LEVEL=debug
//! ```
//!
//! ```ignore
//! // Configuration file
//! log = {
//! // Inject (use) the value of the environment variable LOG_LEVEL
//! level = $"LOG_LEVEL"::str;
//! }
//! ```
//!
//!# Grammar
//!
//! This section describes the configuration input format. The starting rule is `conf`.
Expand Down
188 changes: 184 additions & 4 deletions src/parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -360,7 +360,7 @@ named!(group<&[u8], SettingsList>,
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ~~~ Boolean values parser and auxiliary parsers ~~~
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
named!(boolean_scalar_value<&[u8], ScalarValue>, alt!(bool_true_value | bool_false_value));
named!(boolean_scalar_value<&[u8], ScalarValue>, alt!(bool_true_value | bool_false_value | bool_env_value));

named!(bool_true_value<&[u8], ScalarValue>,
alt!(chain!(
Expand All @@ -374,6 +374,11 @@ named!(bool_true_value<&[u8], ScalarValue>,
alt!(tag!("Y") | tag!("y")) ~
alt!(tag!("E") | tag!("e")) ~
alt!(tag!("S") | tag!("s")),
|| { ScalarValue::Boolean(true) } )
|
chain!(
alt!(tag!("O") | tag!("o")) ~
alt!(tag!("N") | tag!("n")),
|| { ScalarValue::Boolean(true) } )));

named!(bool_false_value<&[u8], ScalarValue>,
Expand All @@ -388,12 +393,47 @@ named!(bool_false_value<&[u8], ScalarValue>,
chain!(
alt!(tag!("N") | tag!("n")) ~
alt!(tag!("O") | tag!("o")),
|| { ScalarValue::Boolean(false) } )
|
chain!(
alt!(tag!("O") | tag!("o")) ~
alt!(tag!("F") | tag!("f")) ~
alt!(tag!("F") | tag!("f")),
|| { ScalarValue::Boolean(false) } )));

// Special boolean parser with syntax $"ENV_VAR_NAME"::bool which assumes the environment
// variable $ENV_VAR_NAME as boolean and try to parse it.
// We do a little hack here to avoid double codding; we call bool_true_value directly
// on the value of the environment variable and iterpret the return value.
named!(bool_env_value<&[u8], ScalarValue>,
chain!(
tag!("$") ~
n: string_literal ~
tag!(":") ~
tag!(":") ~
alt!(tag!("B") | tag!("b")) ~
alt!(tag!("O") | tag!("o")) ~
alt!(tag!("O") | tag!("o")) ~
alt!(tag!("L") | tag!("l")),
|| {
use std::env;
if let Ok(value) = env::var(&n) {
if let IResult::Done(_, output) = bool_true_value(value.as_bytes()) {
output
} else {
ScalarValue::Boolean(false)
}
} else {
ScalarValue::Boolean(false)
}
} ));

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ~~~ String parser and auxiliary parsers ~~~
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
named!(str_scalar_value<&[u8], ScalarValue>,
named!(str_scalar_value<&[u8], ScalarValue>, alt!(string_scalar_value | string_env_value));

named!(string_scalar_value<&[u8], ScalarValue>,
chain!(
strs: many1!(chain!(
s: string_literal ~
Expand All @@ -420,11 +460,31 @@ named!(string_literal<&[u8], String>,
accum
})[..])}));

// Special string parser with syntax $"ENV_VAR_NAME"::str which returns the environment
// variable $ENV_VAR_NAME without any modifications.
named!(string_env_value<&[u8], ScalarValue>,
chain!(
tag!("$") ~
n: string_literal ~
tag!(":") ~
tag!(":") ~
alt!(tag!("S") | tag!("s")) ~
alt!(tag!("T") | tag!("t")) ~
alt!(tag!("R") | tag!("r")),
|| {
use std::env;
if let Ok(value) = env::var(&n) {
ScalarValue::Str(value)
} else {
ScalarValue::Str("".to_string())
}
} ));

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ~~~ Integer values parser and auxiliary parsers ~~~
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
named!(int_scalar_value<&[u8], ScalarValue>,
alt!(int64_scalar_value | int32_scalar_value));
alt!(int64_scalar_value | int32_scalar_value | int_env_value));

// Tentative parser to match Integer32 scalar values
// Returns an `Err` if `parse::<i32>()` fails
Expand Down Expand Up @@ -465,11 +525,39 @@ named!(int64_scalar_value<&[u8], ScalarValue>,
r.map(|v| ScalarValue::Integer64(v))
}));

// Special Integer parser with syntax $"ENV_VAR_NAME"::int which assumes the environment
// variable $ENV_VAR_NAME as Integer and try to parse it. On parsing error it returns Integer32(0).
// We do a little hack here to avoid double codding; we call int32_scalar_value and int64_scalar_value directly
// on the value of the environment variable and iterpret the return value.
named!(int_env_value<&[u8], ScalarValue>,
chain!(
tag!("$") ~
n: string_literal ~
tag!(":") ~
tag!(":") ~
alt!(tag!("I") | tag!("i")) ~
alt!(tag!("N") | tag!("n")) ~
alt!(tag!("T") | tag!("t")),
|| {
use std::env;
if let Ok(value) = env::var(&n) {
if let IResult::Done(_, output) = int64_scalar_value(value.as_bytes()) {
output
} else if let IResult::Done(_, output) = int32_scalar_value(value.as_bytes()) {
output
} else {
ScalarValue::Integer32(0i32)
}
} else {
ScalarValue::Integer32(0i32)
}
} ));

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ~~~ Floating point values parser and auxiliary parsers ~~~
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
named!(flt_scalar_value<&[u8], ScalarValue>,
alt!(flt64_scalar_value | flt32_scalar_value));
alt!(flt64_scalar_value | flt32_scalar_value | flt_env_value));

// Auxiliary parser for floats with digits before .
// [0-9]+\.[0-9]*
Expand Down Expand Up @@ -549,6 +637,34 @@ named!(flt64_scalar_value<&[u8], ScalarValue>,
r.map(|v| ScalarValue::Floating64(v))
}));

// Special Float parser with syntax $"ENV_VAR_NAME"::flt which assumes the environment
// variable $ENV_VAR_NAME as Floating and try to parse it. On parsing error it returns Floating32(0).
// We do a little hack here to avoid double codding; we call flt32_scalar_value and flt64_scalar_value directly
// on the value of the environment variable and iterpret the return value.
named!(flt_env_value<&[u8], ScalarValue>,
chain!(
tag!("$") ~
n: string_literal ~
tag!(":") ~
tag!(":") ~
alt!(tag!("F") | tag!("f")) ~
alt!(tag!("L") | tag!("l")) ~
alt!(tag!("T") | tag!("t")),
|| {
use std::env;
if let Ok(value) = env::var(&n) {
if let IResult::Done(_, output) = flt64_scalar_value(value.as_bytes()) {
output
} else if let IResult::Done(_, output) = flt32_scalar_value(value.as_bytes()) {
output
} else {
ScalarValue::Floating32(0f32)
}
} else {
ScalarValue::Floating32(0f32)
}
} ));

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ~~~ Parser to ignore useless stuff: comments, new lines, ... ~~~
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expand Down Expand Up @@ -3409,4 +3525,68 @@ mod test {

assert_eq!(parsed, Done(&b""[..], Config::new(expected)));
}

#[test]
fn env_scalar_values() {
// Set up environment variables
use std::env;
env::set_var("TEST_BOOL", "Yes");
env::set_var("TEST_INT32", "-42");
env::set_var("TEST_INT64", "+42L");
env::set_var("TEST_FLT32", "3.1415");
env::set_var("TEST_FLT64", "-3.1415L");

// Test boolean
let input = &b"$\"TEST_BOOL\"::bool;\n"[..];
let res = boolean_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Boolean(true)));

let input = &b"$\"TEST_BOOL_NOT_FOUND\"::bool;\n"[..];
let res = boolean_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Boolean(false)));

// Test string
let input = &b"$\"TEST_BOOL\"::str;\n"[..];
let res = str_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Str("Yes".to_string())));

let input = &b"$\"TEST_BOOL_NOT_FOUND\"::str;\n"[..];
let res = str_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Str("".to_string())));

// Test integer
let input = &b"$\"TEST_INT32\"::int;\n"[..];
let res = int_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Integer32(-42i32)));

let input = &b"$\"TEST_INT64\"::int;\n"[..];
let res = int_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Integer64(42i64)));

let input = &b"$\"TEST_INT_NOT_FOUND\"::int;\n"[..];
let res = int_scalar_value(input);
assert_eq!(res, Done(&b";\n"[..], ScalarValue::Integer32(0i32)));

// Test float
let input = &b"$\"TEST_FLT32\"::flt;\n"[..];
if let Done(_, ScalarValue::Floating32(value)) = flt_scalar_value(input) {
assert!(value > 3.1414 && value < 3.1416);
} else {
panic!("Failed to read env f32");
}

let input = &b"$\"TEST_FLT64\"::flt;\n"[..];
if let Done(_, ScalarValue::Floating64(value)) = flt_scalar_value(input) {
assert!(value > -3.1416 && value < -3.1414);
} else {
panic!("Failed to read env f64");
}

let input = &b"$\"TEST_FLT_NOT_FOUND\"::flt;\n"[..];
if let Done(_, ScalarValue::Floating32(value)) = flt_scalar_value(input) {
assert!(value > -0.0001 && value < 0.0001);
} else {
panic!("Failed to read fake env float");
}
}
}

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