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6ff901d7b0
@wythe points out we don't need to keep the around now param_is_set() is removed. We can in fact go further and avoid marshalling them into temporary objects at the caller altogether. This means internally we have an array of struct param, rather than an array of 'struct param *', which causes most of the noise in this patch. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
92 lines
2.8 KiB
C
92 lines
2.8 KiB
C
#ifndef LIGHTNING_LIGHTNINGD_PARAMS_H
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#define LIGHTNING_LIGHTNINGD_PARAMS_H
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#include "config.h"
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#include <ccan/ccan/typesafe_cb/typesafe_cb.h>
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struct param;
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/*
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Typesafe callback system for unmarshalling and validating json parameters.
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Typical usage:
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unsigned cltv;
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const jsmntok_t *note;
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u64 *msatoshi;
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if (!param_parse(cmd, buffer, tokens,
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param_req("cltv", json_tok_number, &cltv),
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param_opt_tok("note", ¬e),
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param_opt("msatoshi", json_tok_u64, &msatoshi),
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NULL))
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return;
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At this point in the code you can be assured the json tokens were successfully
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parsed. If not, param_parse() returns false, having already called
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command_fail() with a descriptive error message. The data section of the json
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result contains the offending parameter and its value.
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cltv is a required parameter, and is set correctly.
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note and msatoshi are optional parameters. Their argument will be set to NULL
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if they are not provided.
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The note parameter uses a special callback, param_opt_tok: it
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simply sets note to the appropriate value (or NULL) and lets the
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handler do the validating.
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There are canned failure messages for common callbacks. An example:
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'msatoshi' should be an unsigned 64 bit integer, not '123z'
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Otherwise a generic message is provided.
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*/
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bool param_parse(struct command *cmd, const char *buffer,
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const jsmntok_t params[], ...);
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/*
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* This callback provided must follow this signature; e.g.,
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* bool json_tok_double(const char *buffer, const jsmntok_t *tok, double *arg)
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*/
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typedef bool(*param_cb)(const char *buffer, const jsmntok_t *tok, void *arg);
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/*
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* Add a handler to unmarshal a required json token into @arg. The handler must
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* return true on success and false on failure. Upon failure, command_fail will be
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* called with a descriptive error message.
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*
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* This operation is typesafe; i.e., a compilation error will occur if the types
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* of @arg and the last parameter of @cb do not match.
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*
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* Returns an opaque pointer that can be later used in param_is_set().
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*/
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#define param_req(name, cb, arg) \
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name"", \
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typesafe_cb_preargs(bool, void *, \
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(cb), (arg), \
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const char *, \
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const jsmntok_t *), \
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(arg), NULL, 0
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/*
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* Same as above but for optional parameters.
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*/
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#define param_opt(ctx, name, cb, arg) \
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name"", \
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typesafe_cb_preargs(bool, void *, \
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(cb), *(arg), \
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const char *, \
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const jsmntok_t *), \
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(arg), (ctx), sizeof(**arg)
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/*
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* For when you want an optional raw token.
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*
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* Note: weird sizeof() does type check that arg really is a (const) jsmntok_t **.
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*/
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#define param_opt_tok(ctx, name, arg) \
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name"", \
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json_tok_tok, \
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(arg) + 0*sizeof(*(arg) == (jsmntok_t *)NULL), \
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(ctx), sizeof(const jsmntok_t *)
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#endif /* LIGHTNING_LIGHTNINGD_PARAMS_H */
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